k214-12.htm

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

Annual Report Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934

For the Fiscal Year Ended: December 31, 2012

Commission file number: 000-29274

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

(Exact name of registrant as specified in its charter)

	State of Minnesota		41-1789725
	(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification No.)

	30 East 7th Street, Suite 1300 St. Paul, Minnesota 55101		(651) 227-7333
	(Address of principal executive offices)		(Registrant’s telephone number)

Securities registered pursuant to Section 12(b) of the Act:

	Title of each class		Name of each exchange on which registered
	None		None

Securities registered pursuant to Section 12(g) of the Act:

	Limited Partnership Units
	(Title of class)

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the

Securities Act. o Yes x No

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or

Section 15(d) of the Exchange Act. o Yes x No

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

x Yes o No

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). x Yes o No

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

o Large accelerated filer	o Accelerated filer
o Non-accelerated filer	x Smaller reporting company

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).

o Yes x No

As of June 30, 2012, there were 22,663.113 Units of limited partnership interest outstanding and owned by nonaffiliates of the registrant, which Units had an aggregate market value (based solely on the price at which they were sold since there is no ready market for such Units) of $22,663,113.

DOCUMENTS INCORPORATED BY REFERENCE

The registrant has not incorporated any documents by reference into this report.

PART I

ITEM 1. BUSINESS.

AEI Income & Growth Fund XXI Limited Partnership (the "Partnership" or the "Registrant") is a limited partnership which was organized pursuant to the laws of the State of Minnesota on August 22, 1994. The registrant is comprised of AEI Fund Management XXI, Inc. (“AFM”) as Managing General Partner, Robert P. Johnson, the President and sole director of AFM, as the Individual General Partner, and purchasers of partnership units as Limited Partners. The Partnership offered for sale up to $24,000,000 of limited partnership interests (the "Units") (24,000 Units at $1,000 per Unit) pursuant to a registration statement effective February 1, 1995. The Partnership commenced operations on April 14, 1995 when minimum subscriptions of 1,500 Limited Partnership Units ($1,500,000) were accepted. On January 31, 1997, the Partnership offering terminated when the maximum subscription limit of 24,000 Limited Partnership Units ($24,000,000) was reached.

The Partnership was organized to acquire existing and newly constructed commercial properties located in the United States, to lease such properties to tenants under net leases, to hold such properties and to eventually sell such properties. From subscription proceeds, the Partnership purchased ten properties including partial interests in seven properties, at a total cost of $19,686,525. The balance of the subscription proceeds was applied to organization and syndication costs, working capital reserves and distributions, which represented a return of capital. The properties are commercial, single tenant buildings leased under net leases.

The Partnership's properties were purchased without any indebtedness. The Partnership will not finance properties in the future to obtain proceeds for new property acquisitions. If it is required to do so, the Partnership may incur short-term indebtedness, which may be secured by a portion of the Partnership's properties, to finance day-to-day cash flow requirements (including cash flow necessary to repurchase Units). The amount of borrowings that may be secured by the properties is limited in the aggregate to 10% of the purchase price of all properties. The Partnership will not incur borrowings to pay distributions and will not incur borrowings while there is cash available for distributions.

The Partnership will hold its properties until the General Partners determine that the sale or other disposition of the properties is advantageous in view of the Partnership's investment objectives. In deciding whether to sell properties, the General Partners will consider factors such as potential appreciation, net cash flow and income tax considerations. The Partnership expects to sell some or all of its properties prior to its final liquidation and to reinvest the proceeds from such sales in additional properties. The Partnership reserves the right, at the discretion of the General Partners, to either distribute proceeds from the sale of properties to the Partners or to reinvest such proceeds in additional properties, provided that sufficient proceeds are distributed to the Limited Partners to pay federal and state income taxes related to any taxable gain recognized as a result of the sale.

Page 2 of 36

ITEM 1. BUSINESS. (Continued)

The prospectus under which Units were initially sold indicated that the General Partners intended to liquidate the Partnership 12 to 15 years after formation, depending upon the then current real estate and money markets, the economic climate and the income tax consequences to the Limited Partners. During the second quarter of 2013, the Managing General Partner anticipates that it will mail a proxy statement to the Limited Partners that will allow them to vote on whether to continue the Partnership for an additional 60 months or to initiate the final disposition, liquidation and distribution of all of the Partnership’s properties and assets within 24 months.

Leases

Although there are variations in the specific terms of the leases, the following is a summary of the general terms of the Partnership's leases. The properties are leased to various tenants under net leases, classified as operating leases. Under a net lease, the tenant is responsible for real estate taxes, insurance, maintenance, repairs and operating expenses for the property. For some leases, the Partnership is responsible for repairs to the structural components of the building, the roof, and the parking lot. At the time the properties were acquired, the remaining primary lease terms varied from 10 to 20 years. The leases provide the tenants with two to five five-year renewal options subject to the same terms and conditions as the primary term. The leases provide for base annual rental payments, payable in monthly installments, and contain rent clauses which entitle the Partnership to receive additional rent in future years based on stated rent increases.

Property Activity During the Last Three Years

As of December 31, 2009, the Partnership owned a significant interest in eleven properties and a minor interest in two properties with a total cost of $18,132,742. During the years ended December 31, 2010, 2011 and 2012, the Partnership sold five property interests and received net sale proceeds of $1,102,212, $1,457,405 and $423,084, which resulted in net gains of $253,923, $467,366 and $69,896, respectively. During 2010, the Partnership expended $1,433,468 to purchase one additional property as it reinvested cash generated from property sales. As of December 31, 2012, the Partnership owned a significant interest in nine properties with a total cost of $16,677,033.

Major Tenants

During 2012, five tenants each contributed more than ten percent of the Partnership's total rental revenue. The major tenants in aggregate contributed 72% of total rental revenue in 2012. It is anticipated that, based on minimum rental payments required under the leases, each major tenant will continue to contribute more than ten percent of rental revenue in 2013 and future years. Any failure of these major tenants could materially affect the Partnership's net income and cash distributions.

Page 3 of 36

ITEM 1. BUSINESS. (Continued)

Competition

The Partnership is a minor factor in the commercial real estate business. There are numerous entities engaged in the commercial real estate business which have greater financial resources than the Partnership. At the time the Partnership elects to dispose of its properties, the Partnership will be in competition with other persons and entities to find buyers for its properties.

Employees

The Partnership has no direct employees. Management services are performed for the Partnership by AEI Fund Management, Inc., an affiliate of AFM.

ITEM 1A. RISK FACTORS.

Not required for a smaller reporting company.

ITEM 1B. UNRESOLVED STAFF COMMENTS.

Not required for a smaller reporting company.

ITEM 2. PROPERTIES.

Investment Objectives

The Partnership's investment objectives are to acquire existing or newly-developed commercial properties throughout the United States that offer the potential for (i) regular cash distributions of lease income; (ii) growth in lease income through rent escalation provisions; (iii) preservation of capital through all-cash sale-leaseback transactions; (iv) capital growth through appreciation in the value of properties; and (v) stable property performance through long-term lease contracts. The Partnership does not have a policy, and there is no limitation, as to the amount or percentage of assets that may be invested in any one property. However, to the extent possible, the General Partners attempt to diversify the type and location of the Partnership's properties.

Description of Properties

The Partnership's properties are commercial, single tenant buildings. The properties were acquired on a debt-free basis and are leased to various tenants under net leases, classified as operating leases. The Partnership holds an undivided fee simple interest in the properties.

The Partnership's properties are subject to the general competitive conditions incident to the ownership of single tenant investment real estate. Since each property is leased under a long-term lease, there is little competition until the Partnership decides to sell the property. At this time, the Partnership will be competing with other real estate owners, on both a national and local level, in attempting to find buyers for the properties. In the event of a tenant default, the Partnership would be competing with other real estate owners, who have property vacancies, to attract a new tenant to lease the property. The Partnership's tenants operate in industries that are very competitive and can be affected by factors such as changes in regional or local economies, seasonality and changes in consumer preference.

Page 4 of 36

ITEM 2. PROPERTIES. (Continued)

The following table is a summary of the properties that the Partnership acquired and owned as of December 31, 2012.

Property	Purchase Date	Property Cost			Tenant	Annual Lease Payment		Annual Rent Per Sq. Ft.

KinderCare Daycare Center Andover, MN	6/14/02	$	1,264,207		KinderCare Learning Centers LLC	$	145,447	$	16.86

Jared Jewelry Store Hanover, MD (50%)	2/9/04	$	1,989,135		Sterling Jewelers Inc.	$	185,406	$	63.83

Jared Jewelry Store Auburn Hills, MI (40%)	1/14/05	$	1,466,048		Sterling Jewelers Inc.	$	112,772	$	48.95

CarMax Auto Superstore Lithia Springs, GA (20%)	3/18/05	$	1,885,231		CarMax Auto Superstores, Inc.	$	146,286	$	38.01

Applebee’s Restaurant Johnstown, PA (62%)	9/21/06	$	1,682,887		B.T. Woodlipp, Inc.	$	130,441	$	40.51

Best Buy Store Eau Claire, WI (54%)	1/31/08	$	3,637,706		Best Buy Stores, L.P.	$	256,001	$	10.01

Fresenius Medical Center Shreveport, LA (55%)	10/2/08	$	1,360,617		Bio-Medical Applications of Louisiana, LLC	$	102,520	$	21.93

Tractor Supply Company Store Rapid City, SD (63%)	8/6/09	$	1,957,734		Tractor Supply Company	$	141,750	$	11.78

Scott & White Clinic College Station, TX (39%)	10/20/10	$	1,433,468	(1)	Scott & White Healthcare	$	120,120	$	22.24

(1) Does not include acquisition costs that were expensed.

The properties listed above with a partial ownership percentage are owned with the following affiliated entities and/or unrelated third parties: Jared Jewelry store in Hanover, Maryland (AEI Net Lease Income & Growth Fund XX Limited Partnership); Jared Jewelry store in Auburn Hills, Michigan (AEI Income & Growth Fund 25 LLC); CarMax auto superstore (AEI Income & Growth Fund 24 LLC, AEI Income & Growth Fund 25 LLC and AEI Private Net Lease Millennium Fund Limited Partnership); Applebee’s restaurant (AEI Income & Growth Fund XXII Limited Partnership); Best Buy store (AEI Income & Growth Fund 23 LLC and AEI Income & Growth Fund 26 LLC); Fresenius Medical Center (AEI Income & Growth Fund 24 LLC); Tractor Supply Company store (AEI Income & Growth Fund 27 LLC) and Scott & White Healthcare (AEI Net Lease Income & Growth Fund XX Limited Partnership and AEI Income & Growth Fund 25 LLC).

Page 5 of 36

ITEM 2. PROPERTIES. (Continued)

The Partnership accounts for properties owned as tenants-in-common with affiliated entities and/or unrelated third parties using the proportionate consolidation method. Each tenant-in-common owns a separate, undivided interest in the properties. Any tenant-in-common that holds more than a 50% interest does not control decisions over the other tenant-in-common interests. The financial statements reflect only this Partnership's percentage share of the properties' land, building and equipment, liabilities, revenues and expenses.

At the time the properties were acquired, the remaining primary lease terms varied from 10 to 20 years. The leases provide the tenants with two to five five-year renewal options subject to the same terms and conditions as the primary term.

Pursuant to the lease agreements, the tenants are required to provide proof of adequate insurance coverage on the properties they occupy. The General Partners believe the properties are adequately covered by insurance and consider the properties to be well-maintained and sufficient for the Partnership's operations.

For tax purposes, the Partnership's properties are depreciated under the Modified Accelerated Cost Recovery System (MACRS). The largest depreciable component of a property is the building which is depreciated, using the straight-line method, over 39 years. The remaining depreciable components of a property are personal property and land improvements which are depreciated, using an accelerated method, over 5 and 15 years, respectively. Since the Partnership has tax-exempt Partners, the Partnership is subject to the rules of Section 168(h)(6) of the Internal Revenue Code which requires a percentage of the properties' depreciable components to be depreciated over longer lives using the straight-line method. In general, the federal tax basis of the properties for tax depreciation purposes is the same as the basis for book depreciation purposes except for properties purchased after January 1, 2009. For those properties, acquisition expenses that were expensed for book purposes were capitalized and added to the basis of the property for tax depreciation purposes.

At December 31, 2012, all properties listed above were 100% occupied.

ITEM 3. LEGAL PROCEEDINGS.

None.

ITEM 4. MINE SAFETY DISCLOSURES.

Not Applicable.

Page 6 of 36

PART II

ITEM 5. MARKET FOR REGISTRANT’S COMMON EQUITY, RELATED STOCK-

HOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES.

(a) As of December 31, 2012, there were 1,215 holders of record of the registrant's Limited Partnership Units. There is no other class of security outstanding or authorized. The registrant's Units are not a traded security in any market. During the period covered by this report, the Partnership did not sell any equity securities that are not registered under the Securities Act of 1933.

Cash distributions of $11,758 and $11,758 were made to the General Partners and $1,163,988 and $1,163,992 were made to the Limited Partners for 2012 and 2011, respectively. The distributions were made on a quarterly basis and represent Net Cash Flow, as defined, except as discussed below. These distributions should not be compared with dividends paid on capital stock by corporations.

As part of the Limited Partners’ distributions discussed above, the Partnership distributed net sale proceeds of $93,728 and $41,138 in 2012 and 2011, respectively.

(b) Not applicable.

(c) Pursuant to Section 7.7 of the Partnership Agreement, each Limited Partner has the right to present Units to the Partnership for purchase by submitting notice to the Managing General Partner during September of each year. The purchase price of the Units is based on a formula specified in the Partnership Agreement. Units tendered to the Partnership are redeemed on October 1st of each year subject to the following limitations. The Partnership will not be obligated to purchase in any year any number of Units that, when aggregated with all other transfers of Units that have occurred since the beginning of the same calendar year (excluding Permitted Transfers as defined in the Partnership Agreement), would exceed 5% of the total number of Units outstanding on January 1 of such year. In no event shall the Partnership be obligated to purchase Units if, in the sole discretion of the Managing General Partner, such purchase would impair the capital or operation of the Partnership.

Small Business Issuer Purchases of Equity Securities

Period	Total Number of Units Purchased	Average Price Paid per Unit	Total Number of Units Purchased as Part of Publicly Announced Plans or Programs	Maximum Number of Units that May Yet Be Purchased Under the Plans or Programs

10/1/12 to 10/31/12	10.00	$260.76	1,346.89(1)	(2)

11/1/12 to 11/30/12	--	--	--	--

12/1/12 to 12/31/12	--	--	--	--

(1)	The Partnership's repurchase plan is mandated by the Partnership Agreement as included in the prospectus related to the original offering of the Units.

(2)	The Partnership Agreement contains annual limitations on repurchases described in the paragraph above and has no expiration date.

Page 7 of 36

ITEM 6. SELECTED FINANCIAL DATA.

Not required for a smaller reporting company.

ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL

CONDITION AND RESULTS OF OPERATIONS.

This section contains "forward-looking statements" which represent management's expectations or beliefs concerning future events, including statements regarding anticipated application of cash, expected returns from rental income, growth in revenue, the sufficiency of cash to meet operating expenses, rates of distribution, and other matters. These, and other forward-looking statements, should be evaluated in the context of a number of factors that may affect the Partnership's financial condition and results of operations, including the following:

—

Market and economic conditions which affect the value of the properties the Partnership owns and the cash from rental income such properties generate;

—

the federal income tax consequences of rental income, deductions, gain on sales and other items and the effects of these consequences for the Partners;

—

resolution by the General Partners of conflicts with which they may be confronted;

—

the success of the General Partners of locating properties with favorable risk return characteristics;

—

the effect of tenant defaults; and

—

the condition of the industries in which the tenants of properties owned by the Partnership operate.

Application of Critical Accounting Policies

The preparation of the Partnership’s financial statements requires management to make estimates and assumptions that may affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent assets and liabilities. Management evaluates these estimates on an ongoing basis, including those related to the carrying value of investments in real estate and the allocation by AEI Fund Management, Inc. of expenses to the Partnership as opposed to other funds they manage.

The Partnership purchases properties and records them in the financial statements at cost (not including acquisition expenses). The Partnership tests long-lived assets for recoverability when events or changes in circumstances indicate that the carrying value may not be recoverable. For properties the Partnership will hold and operate, management determines whether impairment has occurred by comparing the property’s probability-weighted future undiscounted cash flows to its current carrying value. For properties held for sale, management determines whether impairment has occurred by comparing the property’s estimated fair value less cost to sell to its current carrying value. If the carrying value is greater than the net realizable value, an impairment loss is recorded to reduce the carrying value of the property to its net realizable value. Changes in these assumptions or analysis may cause material changes in the carrying value of the properties.

Page 8 of 36

ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS. (Continued)

AEI Fund Management, Inc. allocates expenses to each of the funds they manage primarily on the basis of the number of hours devoted by their employees to each fund’s affairs. They also allocate expenses at the end of each month that are not directly related to a fund’s operations based upon the number of investors in the fund and the fund’s capitalization relative to other funds they manage. The Partnership reimburses these expenses subject to detailed limitations contained in the Partnership Agreement.

Management of the Partnership has discussed the development and selection of the above accounting estimates and the management discussion and analysis disclosures regarding them with the managing partner of the Partnership.

Results of Operations

For the years ended December 31, 2012 and 2011, the Partnership recognized rental income from continuing operations of $1,334,130 and $1,309,549, respectively. In 2012, rental income increased due to additional rent received from rent increases on three properties. Based on the scheduled rent for the properties owned as of February 28, 2013, the Partnership expects to recognize rental income from continuing operations of approximately $1,363,000 in 2013.

For the years ended December 31, 2012 and 2011, the Partnership incurred Partnership administration expenses from affiliated parties of $212,740 and $227,579, respectively. These administration expenses include costs associated with the management of the properties, processing distributions, reporting requirements and communication with the Limited Partners. During the same periods, the Partnership incurred Partnership administration and property management expenses from unrelated parties of $64,487 and $38,889, respectively. These expenses represent direct payments to third parties for legal and filing fees, direct administrative costs, outside audit costs, taxes, insurance and other property costs. The increase in these expenses in 2012, when compared to 2011, is the result of costs incurred to repair the parking lot at one property.

For the years ended December 31, 2012 and 2011, the Partnership recognized interest income of $7,723 and $7,654, respectively.

Upon complete disposal of a property or classification of a property as Real Estate Held for Sale, the Partnership includes the operating results and sale of the property in discontinued operations. In addition, the Partnership reclassifies the prior periods’ operating results of the property to discontinued operations. For the year ended December 31, 2012, the Partnership recognized income from discontinued operations of $88,975, representing rental income less property management expenses of $19,079 and gain on disposal of real estate of $69,896. For the year ended December 31, 2011, the Partnership recognized income from discontinued operations of $553,464, representing rental income less property management expenses and depreciation of $86,098 and gain on disposal of real estate of $467,366.

Page 9 of 36

ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS. (Continued)

On January 19, 2011, the Partnership sold its remaining 0.1534% interest in the Champps Americana restaurant in Livonia, Michigan to an unrelated third party. The Partnership received net sale proceeds of $7,861, which resulted in a net gain of $3,904. The cost and related accumulated depreciation of the interest sold was $6,366 and $2,409, respectively.

On March 25, 2011, the Partnership sold its remaining 44.5116% interest in the KinderCare daycare center in Ballwin, Missouri, in two separate transactions, to unrelated third parties. The Partnership received total net sale proceeds of $902,133, which resulted in a net gain of $362,374. The cost and related accumulated depreciation of the interests sold was $675,587 and $135,828, respectively.

During 2011, the Partnership sold 11.5987% of the Winn-Dixie store in Panama City, Florida, in four separate transactions, to unrelated third parties. The Partnership received total net sale proceeds of $547,411, which resulted in a net gain of $101,088. The cost and related accumulated depreciation of the interests sold was $537,605 and $91,282, respectively.

During 2012, the Partnership sold its remaining 8.8038% interest in the Winn-Dixie store in Panama City, Florida, in three separate transactions, to unrelated third parties. The Partnership received total net sale proceeds of $406,884, which resulted in a net gain of $68,108. The cost and related accumulated depreciation of the interests sold was $408,060 and $69,284, respectively. At December 31, 2011, the property was classified as Real Estate Held for Sale with a carrying value of $338,776.

On February 3, 2012, the Partnership sold its remaining 2.6811% interest in the Arby’s restaurant in Montgomery, Alabama to an unrelated third party. The Partnership received net sale proceeds of $16,200, which resulted in a net gain of $1,788. The cost and related accumulated depreciation of the interest sold was $23,049 and $8,637, respectively.

Management believes inflation has not significantly affected income from operations. Leases may contain rent increases, based on the increase in the Consumer Price Index over a specified period, which will result in an increase in rental income over the term of the leases. Inflation also may cause the real estate to appreciate in value. However, inflation and changing prices may have an adverse impact on the operating margins of the properties' tenants, which could impair their ability to pay rent and subsequently reduce the Net Cash Flow available for distributions.

Liquidity and Capital Resources

During the years ended December 31, 2012 and 2011, the Partnership's cash balances increased $325,057 and $1,419,965, respectively, as a result of cash generated from the sale of property, which was partially offset by distributions paid to the Partners in excess of cash generated from operating activities.

Page 10 of 36

ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS. (Continued)

Net cash provided by operating activities decreased from $1,142,483 in 2011 to $1,080,348 in 2012 as a result of a decrease in total rental and interest income in 2012, an increase in Partnership administration and property management expenses in 2012 and net timing differences in the collection of payments from the tenants and the payment of expenses.

The major components of the Partnership's cash flow from investing activities are investments in real estate and proceeds from the sale of real estate. During the years ended December 31, 2012 and 2011, the Partnership generated cash flow from the sale of real estate of $423,084 and $1,457,405, respectively.

The Partnership's primary use of cash flow, other than investment in real estate, is distribution and redemption payments to Partners. The Partnership declares its regular quarterly distributions before the end of each quarter and pays the distribution in the first week after the end of each quarter. The Partnership attempts to maintain a stable distribution rate from quarter to quarter. Redemption payments are paid to redeeming Partners in the fourth quarter of each year.

For the years ended December 31, 2012 and 2011, the Partnership declared distributions of $1,175,746 and $1,175,750, respectively, which were distributed 99% to the Limited Partners and 1% to the General Partners. The Limited Partners received distributions of $1,163,988 and $1,163,992 and the General Partners received distributions of $11,758 and $11,758 for the years, respectively.

During 2012 and 2011, the Partnership distributed net sale proceeds of $94,675 and $41,554 to the Limited and General Partners as part of their quarterly distributions, which represented a return of capital of $4.14 and $1.81 per Limited Partnership Unit, respectively. The Partnership anticipates the remaining net sale proceeds will either be reinvested in additional property or distributed to the Partners in the future.

The Partnership may acquire Units from Limited Partners who have tendered their Units to the Partnership. Such Units may be acquired at a discount. The Partnership will not be obligated to purchase in any year any number of Units that, when aggregated with all other transfers of Units that have occurred since the beginning of the same calendar year (excluding Permitted Transfers as defined in the Partnership Agreement), would exceed 5% of the total number of Units outstanding on January 1 of such year. In no event shall the Partnership be obligated to purchase Units if, in the sole discretion of the Managing General Partner, such purchase would impair the capital or operation of the Partnership.

During 2012, two Limited Partners redeemed a total of 10 Partnership Units for $2,607 in accordance with the Partnership Agreement. During, 2011, one Limited Partner redeemed a total of 10.5 Partnership Units for $3,127. The Partnership acquired these Units using Net Cash Flow from operations. In prior years, a total of 66 Limited Partners redeemed 1,326.39 Partnership Units for $993,269. The redemptions increase the remaining Limited Partners' ownership interest in the Partnership. As a result of these redemption payments and pursuant to the Partnership Agreement, the General Partners received distributions of $27 and $32 in 2012 and 2011, respectively.

Page 11 of 36

ITEM 7. MANAGEMENT'S DISCUSSION AND ANALYSIS. (Continued)

The continuing rent payments from the properties, together with cash generated from property sales, should be adequate to fund continuing distributions and meet other Partnership obligations on both a short-term and long-term basis.

The Economy and Market Conditions

The impact of conditions in the economy over the last few years, including the turmoil in the credit markets, has adversely affected many real estate investment funds. However, the absence of mortgage financing on the Partnership's properties eliminates the risks of foreclosure and debt-refinancing that can negatively impact the value and distributions of leveraged real estate investment funds. Nevertheless, a prolonged economic downturn may adversely affect the operations of the Partnership's tenants and their cash flows. If a tenant were to default on its lease obligations, the Partnership's income would decrease, its distributions would likely be reduced and the value of its properties might decline.

Off-Balance Sheet Arrangements

As of December 31, 2012 and 2011, the Partnership had no material off-balance sheet arrangements that had or are reasonably likely to have current or future effects on its financial condition, results of operations, liquidity or capital resources.

ITEM 7A. QUANTITATIVE & QUALITATIVE DISCLOSURES ABOUT MARKET RISK.

Not required for a smaller reporting company.

ITEM 8. FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

See accompanying index to financial statements.

Page 12 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

INDEX TO FINANCIAL STATEMENTS

		Page

Report of Independent Registered Public Accounting Firm		14

Balance Sheet as of December 31, 2012 and 2011		15

Statements for the Years Ended December 31, 2012 and 2011:

	Income	16

	Cash Flows	17

	Changes in Partners’ Capital	18

Notes to Financial Statements		19 – 28

Page 13 of 36

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Partners:

AEI Income & Growth Fund XXI Limited Partnership

St. Paul, Minnesota

We have audited the accompanying balance sheet of AEI Income & Growth Fund XXI Limited Partnership (a Minnesota limited partnership) as of December 31, 2012 and 2011, and the related statements of income, cash flows and changes in partners' capital for each of the years then ended. The Partnership’s management is responsible for these financial statements. Our responsibility is to express an opinion on these financial statements based on our audits.

We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. The partnership is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. Our audits included consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the company’s internal control over financial reporting. Accordingly, we express no such opinion. An audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.

In our opinion, the financial statements referred to above present fairly, in all material respects, the financial position of AEI Income & Growth Fund XXI Limited Partnership as of December 31, 2012 and 2011, and the results of its operations and its cash flows for each of the years then ended, in conformity with accounting principles generally accepted in the United States of America.

	/s/ BOULAY, HEUTAMKER, ZIBELL & CO. P.L.L.P.
	Boulay, Heutmaker, Zibell & Co. P.L.L.P.
	Certified Public Accountants

Minneapolis, Minnesota
March 29, 2013

Page 14 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

BALANCE SHEET

ASSETS

		December 31,		December 31,
		2012		2011
Current Assets:
Cash	$	2,259,911	$	1,934,854

Real Estate Held for Investment:
Land		4,403,667		4,413,700
Buildings and Equipment		12,273,366		12,286,382
Accumulated Depreciation		(2,930,639)		(2,448,341)
Real Estate Held for Investment, Net		13,746,394		14,251,741
Real Estate Held for Sale		0		338,776
Total Real Estate		13,746,394		14,590,517
Total Assets	$	16,006,305	$	16,525,371

LIABILITIES AND PARTNERS' CAPITAL

Current Liabilities:
Payable to AEI Fund Management, Inc.	$	41,189	$	34,777
Distributions Payable		293,940		293,935
Unearned Rent		12,120		21,889
Total Current Liabilities		347,249		350,601

Partners’ Capital:
General Partners		686		4,646
Limited Partners – 24,000 Units authorized; 22,653 and 22,663 Units issued and outstanding in 2012 and 2011, respectively		15,658,370		16,170,124
Total Partners' Capital		15,659,056		16,174,770
Total Liabilities and Partners' Capital	$	16,006,305	$	16,525,371

The accompanying Notes to Financial Statements are an integral part of this statement.

Page 15 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

STATEMENT OF INCOME

		Year Ended December 31
		2012		2011

Rental Income	$	1,334,130	$	1,309,549

Expenses:
Partnership Administration – Affiliates		212,740		227,579
Partnership Administration and Property Management – Unrelated Parties		64,487		38,889
Depreciation		490,935		490,935
Total Expenses		768,162		757,403

Operating Income		565,968		552,146

Other Income:
Interest Income		7,723		7,654

Income from Continuing Operations		573,691		559,800

Income from Discontinued Operations		88,975		553,464

Net Income	$	662,666	$	1,113,264

Net Income Allocated:
General Partners	$	7,825	$	13,823
Limited Partners		654,841		1,099,441
Total	$	662,666	$	1,113,264

Income per Limited Partnership Unit:
Continuing Operations	$	25.06	$	24.45
Discontinued Operations		3.84		24.05
Total – Basic and Diluted	$	28.90	$	48.50

Weighted Average Units Outstanding – Basic and Diluted		22,661		22,671

The accompanying Notes to Financial Statements are an integral part of this statement.

Page 16 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

STATEMENT OF CASH FLOWS

		Year Ended December 31
		2012		2011

Cash Flows from Operating Activities:
Net Income	$	662,666	$	1,113,264

Adjustments to Reconcile Net Income To Net Cash Provided by Operating Activities:
Depreciation		490,935		491,456
Gain on Sale of Real Estate		(69,896)		(467,366)
Increase (Decrease) in Payable to AEI Fund Management, Inc.		6,412		10,250
Increase (Decrease) in Unearned Rent		(9,769)		(5,121)
Total Adjustments		417,682		29,219
Net Cash Provided By Operating Activities		1,080,348		1,142,483

Cash Flows from Investing Activities:
Proceeds from Sale of Real Estate		423,084		1,457,405

Cash Flows from Financing Activities:
Distributions Paid to Partners		(1,175,741)		(1,176,764)
Redemption Payments		(2,634)		(3,159)
Net Cash Used For Financing Activities		(1,178,375)		(1,179,923)

Net Increase (Decrease) in Cash		325,057		1,419,965

Cash, beginning of year		1,934,854		514,889

Cash, end of year	$	2,259,911	$	1,934,854

The accompanying Notes to Financial Statements are an integral part of this statement.

Page 17 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

STATEMENT OF CHANGES IN PARTNERS' CAPITAL

		General Partners		Limited Partners		Total	Limited Partnership Units Outstanding


Balance, December 31, 2010	$	2,613	$	16,237,802	$	16,240,415	22,673.61

Distributions Declared		(11,758)		(1,163,992)		(1,175,750)

Redemption Payments		(32)		(3,127)		(3,159)	(10.50)

Net Income		13,823		1,099,441		1,113,264

Balance, December 31, 2011		4,646		16,170,124		16,174,770	22,663.11

Distributions Declared		(11,758)		(1,163,988)		(1,175,746)

Redemption Payments		(27)		(2,607)		(2,634)	(10.00)

Net Income		7,825		654,841		662,666

Balance, December 31, 2012	$	686	$	15,658,370	$	15,659,056	22,653.11

The accompanying Notes to Financial Statements are an integral part of this statement.

Page 18 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(1) Organization –

AEI Income & Growth Fund XXI Limited Partnership (“Partnership”) was formed to acquire and lease commercial properties to operating tenants. The Partnership's operations are managed by AEI Fund Management XXI, Inc. (“AFM”), the Managing General Partner. Robert P. Johnson, the President and sole director of AFM, serves as the Individual General Partner. AFM is a wholly owned subsidiary of AEI Capital Corporation of which Mr. Johnson is the majority shareholder. AEI Fund Management, Inc. (“AEI”), an affiliate of AFM, performs the administrative and operating functions for the Partnership.

The terms of the Partnership offering called for a subscription price of $1,000 per Limited Partnership Unit, payable on acceptance of the offer. The Partnership commenced operations on April 14, 1995 when minimum subscriptions of 1,500 Limited Partnership Units ($1,500,000) were accepted. On January 31, 1997, the offering terminated when the maximum subscription limit of 24,000 Limited Partnership Units was reached. Under the terms of the Limited Partnership Agreement, the Limited Partners and General Partners contributed funds of $24,000,000 and $1,000, respectively.

During operations, any Net Cash Flow, as defined, which the General Partners determine to distribute will be distributed 90% to the Limited Partners and 10% to the General Partners; provided, however, that such distributions to the General Partners will be subordinated to the Limited Partners first receiving an annual, noncumulative distribution of Net Cash Flow equal to 10% of their Adjusted Capital Contribution, as defined, and, provided further, that in no event will the General Partners receive less than 1% of such Net Cash Flow per annum. Distributions to Limited Partners will be made pro rata by Units.

Any Net Proceeds of Sale, as defined, from the sale or financing of properties which the General Partners determine to distribute will, after provisions for debts and reserves, be paid in the following manner: (i) first, 99% to the Limited Partners and 1% to the General Partners until the Limited Partners receive an amount equal to: (a) their Adjusted Capital Contribution plus (b) an amount equal to 10% of their Adjusted Capital Contribution per annum, cumulative but not compounded, to the extent not previously distributed from Net Cash Flow; (ii) any remaining balance will be distributed 90% to the Limited Partners and 10% to the General Partners. Distributions to the Limited Partners will be made pro rata by Units.

For tax purposes, profits from operations, other than profits attributable to the sale, exchange, financing, refinancing or other disposition of property, will be allocated first in the same ratio in which, and to the extent, Net Cash Flow is distributed to the Partners for such year. Any additional profits will be allocated in the same ratio as the last dollar of Net Cash Flow is distributed. Net losses from operations will be allocated 99% to the Limited Partners and 1% to the General Partners.

Page 19 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(1) Organization – (Continued)

For tax purposes, profits arising from the sale, financing, or other disposition of property will be allocated in accordance with the Partnership Agreement as follows: (i) first, to those partners with deficit balances in their capital accounts in an amount equal to the sum of such deficit balances; (ii) second, 99% to the Limited Partners and 1% to the General Partners until the aggregate balance in the Limited Partners' capital accounts equals the sum of the Limited Partners' Adjusted Capital Contributions plus an amount equal to 10% of their Adjusted Capital Contributions per annum, cumulative but not compounded, to the extent not previously allocated; (iii) third, the balance of any remaining gain will then be allocated 90% to the Limited Partners and 10% to the General Partners. Losses will be allocated 98% to the Limited Partners and 2% to the General Partners.

The General Partners are not required to currently fund a deficit capital balance. Upon liquidation of the Partnership or withdrawal by a General Partner, the General Partners will contribute to the Partnership an amount equal to the lesser of the deficit balances in their capital accounts or 1% of total Limited Partners' and General Partners' capital contributions.

(2) Summary of Significant Accounting Policies –

Financial Statement Presentation

The accounts of the Partnership are maintained on the accrual basis of accounting for both federal income tax purposes and financial reporting purposes.

Accounting Estimates

Management uses estimates and assumptions in preparing these financial statements in accordance with generally accepted accounting principles. Those estimates and assumptions may affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported revenues and expenses. Actual results could differ from those estimates. Significant items, subject to such estimates and assumptions, include the carrying value of real estate held for investment and real estate held for sale.

The Partnership regularly assesses whether market events and conditions indicate that it is reasonably possible to recover the carrying amounts of its investments in real estate from future operations and sales. A change in those market events and conditions could have a material effect on the carrying amount of its real estate.

Cash Concentrations of Credit Risk

The Partnership's cash is deposited in one financial institution and at times during the year it may exceed FDIC insurance limits.

Page 20 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(2) Summary of Significant Accounting Policies – (Continued)

Receivables

Credit terms are extended to tenants in the normal course of business. The Partnership performs ongoing credit evaluations of its customers’ financial condition and, generally, requires no collateral.

Receivables are recorded at their estimated net realizable value. The Partnership follows a policy of providing an allowance for doubtful accounts; however, based on historical experience, and its evaluation of the current status of receivables, the Partnership is of the belief that such accounts, if any, will be collectible in all material respects and thus an allowance is not necessary. Accounts are considered past due if payment is not made on a timely basis in accordance with the Partnership’s credit terms. Receivables considered uncollectible are written off.

Income Taxes

The income or loss of the Partnership for federal income tax reporting purposes is includable in the income tax returns of the partners. In general, no recognition has been given to income taxes in the accompanying financial statements.

The tax return and the amount of distributable Partnership income or loss are subject to examination by federal and state taxing authorities. If such an examination results in changes to distributable Partnership income or loss, the taxable income of the partners would be adjusted accordingly. Primarily due to its tax status as a partnership, the Partnership has no significant tax uncertainties that require recognition or disclosure. The Partnership is no longer subject to U.S. federal income tax examinations for tax years before 2009, and with few exceptions, is no longer subject to state tax examinations for tax years before 2009.

Revenue Recognition

The Partnership's real estate is leased under net leases, classified as operating leases. The leases provide for base annual rental payments payable in monthly installments. The Partnership recognizes rental revenue according to the terms of the individual leases. For leases that contain stated rental increases, the increases are recognized in the year in which they are effective. Contingent rental payments are recognized when the contingencies on which the payments are based are satisfied and the rental payments become due under the terms of the leases.

Page 21 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(2) Summary of Significant Accounting Policies – (Continued)

Real Estate

The Partnership purchases properties and records them at cost. The Partnership tests real estate for recoverability when events or changes in circumstances indicate that the carrying value may not be recoverable. For properties the Partnership will hold and operate, it compares the carrying amount of the property to the estimated probability-weighted future undiscounted cash flows expected to result from the property and its eventual disposition. If the sum of the expected future cash flows is less than the carrying amount of the property, the Partnership recognizes an impairment loss by the amount by which the carrying amount of the property exceeds the fair value of the property. For properties held for sale, the Partnership determines whether impairment has occurred by comparing the property’s estimated fair value less cost to sell to its current carrying value. If the carrying value is greater than the net realizable value, an impairment loss is recorded to reduce the carrying value of the property to its net realizable value.

The buildings and equipment of the Partnership are depreciated using the straight-line method for financial reporting purposes based on estimated useful lives of 25 years and 5 years, respectively.

The Partnership’s properties are subject to environmental laws and regulations adopted by various governmental entities in the jurisdiction in which the properties are located. These laws could require the Partnership to investigate and remediate the effects of the release or disposal of hazardous materials at these locations if found. For each property, an environmental assessment is completed prior to acquisition. In addition, the lease agreements typically strictly prohibit the production, handling, or storage of hazardous materials (except where incidental to the tenant’s business such as use of cleaning supplies) in violation of applicable law to restrict environmental and other damage. Environmental liabilities are recorded when it is determined the liability is probable and the costs can reasonably be estimated. There were no environmental issues noted or liabilities recorded at December 31, 2012 and 2011.

Page 22 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(2) Summary of Significant Accounting Policies – (Continued)

Fair Value Measurements

As of December 31, 2012, the Partnership had no assets or liabilities measured at fair value on a recurring basis or nonrecurring basis.

Recently Issued Accounting Pronouncements

Management has reviewed recently issued, but not yet effective, accounting pronouncements and does not expect the implementation of these pronouncements to have a significant effect on the Partnership’s financial statements.

Reclassification

Certain items related to discontinued operations in the prior year’s financial statements have been reclassified to conform to 2012 presentation. These reclassifications had no effect on Partners’ capital, net income or cash flows.

(3) Related Party Transactions –

The Partnership owns the percentage interest shown below in the following properties as tenants-in-common with the affiliated entities listed: Jared Jewelry store in Hanover, Maryland (50% – AEI Net Lease Income & Growth Fund XX Limited Partnership); Jared Jewelry store in Auburn Hills, Michigan (40% – AEI Income & Growth Fund 25 LLC); CarMax auto superstore (20% – AEI Income & Growth Fund 24 LLC, AEI Income & Growth Fund 25 LLC and AEI Private Net Lease Millennium Fund Limited Partnership); Applebee’s restaurant (62% – AEI Income & Growth Fund XXII Limited Partnership); Best Buy store (54% – AEI Income & Growth Fund 23 LLC and AEI Income & Growth Fund 26 LLC); Fresenius Medical Center (55% – AEI Income & Growth Fund 24 LLC); Tractor Supply Company store (63% – AEI Income & Growth Fund 27 LLC); and Scott & White Clinic (39% – AEI Net Lease Income & Growth Fund XX Limited Partnership and AEI Income & Growth Fund 25 LLC).

As of December 31, 2010, the Partnership owned a 20.4025% interest in a Winn-Dixie store. The remaining interests in this property are owned by unrelated third parties. AEI Net Lease Income & Growth Fund XIX Limited Partnership, an affiliate of the Partnership, owned a 37% interest in this property until the interest was sold, in a series of transactions, to unrelated third parties in 2009, 2010 and 2011.

Page 23 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(3) Related Party Transactions – (Continued)

AEI received the following reimbursements for costs and expenses from the Partnership for the years ended December 31:

			2012		2011

a.	AEI is reimbursed for costs incurred in providing services related to managing the Partnership's operations and properties, maintaining the Partnership's books, and communicating with the Limited Partners.	$	212,740	$	227,579

b.	AEI is reimbursed for all direct expenses it paid on the Partnership's behalf to third parties related to Partnership administration and property management. These expenses included printing costs, legal and filing fees, direct administrative costs, outside audit costs, taxes, insurance and other property costs. These amounts included $1,150 and $2,302 of expenses related to Discontinued Operations in 2012 and 2011, respectively.	$	65,637	$	41,191

c.	AEI is reimbursed for costs incurred in providing services related to the sale of property.	$	21,329	$	71,866

The payable to AEI Fund Management, Inc. represents the balance due for the services described in 3a, b and c. This balance is non-interest bearing and unsecured and is to be paid in the normal course of business.

(4) Real Estate Held for Investment –

The Partnership leases its properties to various tenants under net leases, classified as operating leases. Under a net lease, the tenant is responsible for real estate taxes, insurance, maintenance, repairs and operating expenses for the property. For some leases, the Partnership is responsible for repairs to the structural components of the building, the roof, and the parking lot. At the time the properties were acquired, the remaining primary lease terms varied from 10 to 20 years. The leases provide the tenants with two to five five-year renewal options subject to the same terms and conditions as the primary term.

Page 24 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(4) Real Estate Held for Investment – (Continued)

The Partnership's properties are commercial, single-tenant buildings. The KinderCare daycare center in Andover, Minnesota was constructed in 1998 and acquired in 2002. The Jared Jewelry store in Hanover, Maryland was constructed in 2001 and acquired in 2004. The Jared Jewelry store in Auburn Hills, Michigan was constructed in 1999 and acquired in 2005. The CarMax auto superstore was constructed in 2003 and acquired in 2005. The Applebee’s restaurant in Johnstown, Pennsylvania was constructed in 1996 and acquired in 2006. The Best Buy store was constructed in 1990, renovated in 1997 and acquired in 2008. The Fresenius Medical Center was constructed and acquired in 2008. The land for the Tractor Supply Company store was acquired in 2008 and construction of the store was completed in 2009. The Scott & White Clinic was constructed and acquired in 2010. There have been no costs capitalized as improvements subsequent to the acquisitions.

The cost of the properties not held for sale and related accumulated depreciation at December 31, 2012 are as follows:

Property	Land		Buildings and Equipment		Total		Accumulated Depreciation

KinderCare, Andover, MN	$	179,755	$	1,084,452	$	1,264,207	$	457,276
Jared Jewelry, Hanover, MD		861,065		1,128,070		1,989,135		400,466
Jared Jewelry, Auburn Hills, MI		280,993		1,185,055		1,466,048		377,241
CarMax, Lithia Springs, GA		815,180		1,070,051		1,885,231		333,499
Applebee’s, Johnstown, PA		431,754		1,251,133		1,682,887		314,867
Best Buy, Eau Claire, WI		853,357		2,784,349		3,637,706		547,589
Fresenius Medical Center, Shreveport, LA		102,046		1,258,571		1,360,617		213,958
Tractor Supply, Rapid City, SD		588,967		1,368,767		1,957,734		184,785
Scott & White, College Station, TX		290,550		1,142,918		1,433,468		100,958
	$	4,403,667	$	12,273,366	$	16,677,033	$	2,930,639

For properties owned as of December 31, 2012, the minimum future rent payments required by the leases are as follows:

2013	$	1,358,017
2014		1,366,157
2015		1,386,254
2016		1,398,713
2017		1,345,950
Thereafter		3,874,323
	$	10,729,414

There were no contingent rents recognized in 2012 and 2011.

Page 25 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(5) Major Tenants –

The following schedule presents rent revenue from individual tenants, or affiliated groups of tenants, who each contributed more than ten percent of the Partnership's total rent revenue for the years ended December 31:

Tenants	Industry		2012		2011

Sterling Jewelers Inc.	Retail	$	298,178	$	286,707
Best Buy Stores, L.P.	Retail		256,000		256,001
CarMax Auto Superstores, Inc.	Retail		146,286		146,612
Tractor Supply Company	Retail		141,750		141,750
KinderCare Learning Centers LLC	Child Care		138,836		148,537
Aggregate rent revenue of major tenants		$	981,050	$	979,607
Aggregate rent revenue of major tenants as a percentage of total rent revenue			72%		70%

(6) Discontinued Operations –

Page 26 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(6) Discontinued Operations – (Continued)

The financial results for these properties are reflected as Discontinued Operations in the accompanying financial statements. The following are the results of discontinued operations for the years ended December 31:

		2012		2011

Rental Income	$	20,229	$	88,921
Property Management Expenses		(1,150)		(2,302)
Depreciation		0		(521)
Gain on Disposal of Real Estate		69,896		467,366
Income from Discontinued Operations	$	88,975	$	553,464

(7) Partners’ Capital –

For the years ended December 31, 2012 and 2011, the Partnership declared distributions of $1,175,746 and $1,175,750, respectively. The Limited Partners received distributions of $1,163,988 and $1,163,992 and the General Partners received distributions of $11,758 and $11,758 for the years, respectively. The Limited Partners' distributions represent $51.37 and $51.34 per Limited Partnership Unit outstanding using 22,661 and 22,671 weighted average Units in 2012 and 2011, respectively. The distributions represent $28.78 and $48.36 per Unit of Net Income and $22.59 and $2.98 per Unit of return of capital in 2012 and 2011, respectively.

As part of the Limited Partners’ distributions discussed above, the Partnership distributed net sale proceeds of $93,728 and $41,138 in 2012 and 2011, respectively.

Page 27 of 36

AEI INCOME & GROWTH FUND XXI LIMITED PARTNERSHIP

NOTES TO FINANCIAL STATEMENTS

DECEMBER 31, 2012 AND 2011

(7) Partners’ Capital – (Continued)

During 2012, two Limited Partners redeemed a total of 10 Partnership Units for $2,607 in accordance with the Partnership Agreement. During 2011, one Limited Partner redeemed a total of 10.5 Partnership Units for $3,127. The Partnership acquired these Units using Net Cash Flow from operations. The redemptions increase the remaining Limited Partners' ownership interest in the Partnership. As a result of these redemption payments and pursuant to the Partnership Agreement, the General Partners received distributions of $27 and $32 in 2012 and 2011, respectively.

After the effect of redemptions, the Adjusted Capital Contribution, as defined in the Partnership Agreement, is $1,059.46 per original $1,000 invested.

(8) Income Taxes –

The following is a reconciliation of net income for financial reporting purposes to income reported for federal income tax purposes for the years ended December 31:

		2012		2011

Net Income for Financial Reporting Purposes	$	662,666	$	1,113,264

Depreciation for Tax Purposes Under Depreciation for Financial Reporting Purposes		146,997		126,168

Income Accrued for Tax Purposes Under Income for Financial Reporting Purposes		(9,768)		(5,122)

Gain on Sale of Real Estate for Tax Purposes Over Gain for Financial Reporting Purposes		1,621		33,870
Taxable Income to Partners	$	801,516	$	1,268,180

The following is a reconciliation of Partners' capital for financial reporting purposes to Partners' capital reported for federal income tax purposes for the years ended December 31:

		2012		2011

Partners' Capital for Financial Reporting Purposes	$	15,659,056	$	16,174,770

Adjusted Tax Basis of Investments in Real Estate Over Net Investments in Real Estate for Financial Reporting Purposes		938,887		790,269

Income Accrued for Tax Purposes Over Income for Financial Reporting Purposes		12,120		21,888

Syndication Costs Treated as Reduction of Capital For Financial Reporting Purposes		3,208,043		3,208,043
Partners' Capital for Tax Reporting Purposes	$	19,818,106	$	20,194,970

Page 28 of 36

ITEM 9. CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON

ACCOUNTING AND FINANCIAL DISCLOSURE.

None.

ITEM 9A. CONTROLS AND PROCEDURES.

(a) Disclosure Controls and Procedures.

Under the supervision and with the participation of management, including its President and Chief Financial Officer, the Managing General Partner of the Partnership evaluated the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rule 13a-15(e) under the Securities Exchange Act of 1934 (the “Exchange Act”)). Based upon that evaluation, the President and Chief Financial Officer of the Managing General Partner concluded that, as of the end of the period covered by this report, our disclosure controls and procedures were effective in ensuring that information required to be disclosed by us in the reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in applicable rules and forms and that such information is accumulated and communicated to management, including the President and Chief Financial Officer of the Managing General Partner, in a manner that allows timely decisions regarding required disclosure.

(b) Internal Control Over Financial Reporting.

(i) Management’s Report on Internal Control Over Financial Reporting. The Managing General Partner, through its management, is responsible for establishing and maintaining adequate internal control over our financial reporting, as defined in Rule 13a-15(f) under the Exchange Act, and for performing an assessment of the effectiveness of our internal control over financial reporting as of December 31, 2012. Internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. Our system of internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the Partnership; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the Partnership are being made only in accordance with authorizations of management of the Managing General Partner; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the Partnership's assets that could have a material effect on the financial statements.

Management of the Managing General Partner performed an assessment of the effectiveness of our internal control over financial reporting as of December 31, 2012 based upon criteria in Internal Control-Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (“COSO”). Based on our assessment, management of the Managing General Partner determined that our internal control over financial reporting was effective as of December 31, 2012 based on the criteria in Internal Control-Integrated Framework issued by the COSO.

Page 29 of 36

ITEM 9A. CONTROLS AND PROCEDURES. (Continued)

This annual report does not include an attestation report of our registered public accounting firm regarding internal control over financial reporting. Management’s report was not subject to attestation by our registered public accounting firm pursuant to rules of the Securities and Exchange Commission that permit us to provide only management’s report in this annual report.

(ii) Changes in Internal Control Over Financial Reporting. During the most recent period covered by this report, there has been no change in our internal control over financial reporting (as defined in Rule 13a-15(f) under the Exchange Act) that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

ITEM 9B. OTHER INFORMATION.

None.

PART III

ITEM 10. DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE.

The registrant is a limited partnership and has no officers, directors, or direct employees. The General Partners manage and control the Partnership's affairs and have general responsibility and the ultimate authority in all matters affecting the Partnership's business. The General Partners are AEI Fund Management XXI, Inc. (“AFM”), the Managing General Partner, and Robert P. Johnson, Chief Executive Officer, President and sole director of AFM, the Individual General Partner. AFM is a wholly owned subsidiary of AEI Capital Corporation of which Mr. Johnson is the majority shareholder. AFM has only one senior financial executive, its Chief Financial Officer. The Chief Financial Officer reports directly to Mr. Johnson and is accountable for his actions to Mr. Johnson. Although Mr. Johnson and AFM require that all of their personnel, including the Chief Financial Officer, engage in honest and ethical conduct, ensure full, fair, accurate, timely, and understandable disclosure, comply with all applicable governmental laws, rules and regulations, and report to Mr. Johnson any deviation from these principles, because the organization is composed of only approximately 40 individuals, because the management of a partnership by an entity that has different interests in distributions and income than investors involves numerous conflicts of interest that must be resolved on a daily basis, and because the ultimate decision maker in all instances is Mr. Johnson, AFM has not adopted a formal code of conduct. Instead, the materials pursuant to which investors purchase Units disclose these conflicts of interest in detail and Mr. Johnson, as the CEO and sole director of AFM, resolves conflicts to the best of his ability, consistent with his fiduciary obligations to AFM and the fiduciary obligations of AFM to the Partnership. The director and officers of AFM are as follows:

Page 30 of 36

ITEM 10. DIRECTORS, EXECUTIVE OFFICERS AND CORPORATE GOVERNANCE.

(Continued)

Robert P. Johnson, age 68, is Chief Executive Officer, President and sole director and has held these positions since the formation of AFM in August 1994, and has been elected to continue in these positions until December 2013. From 1970 to the present, he has been employed exclusively in the investment industry, specializing in limited partnership investments. In that capacity, he has been involved in the development, analysis, marketing and management of public and private investment programs investing in net lease properties as well as public and private investment programs investing in energy development. Since 1971, Mr. Johnson has been the president, a director and a registered principal of AEI Securities, Inc., which is registered with the SEC as a securities broker-dealer, is a member of the Financial Industry Regulatory Authority (FINRA) and is a member of the Security Investors Protection Corporation (SIPC). Mr. Johnson has been president, a director and the principal shareholder of AEI Fund Management, Inc., a real estate management company founded by him, since 1978. Mr. Johnson is currently a general partner or principal of the general partner in nine limited partnerships and a managing member in five LLCs.

Patrick W. Keene, age 53, is Chief Financial Officer, Treasurer and Secretary and has held these positions since January 22, 2003 and has been elected to continue in these positions until December 2013. Mr. Keene has been employed by AEI Fund Management, Inc. and affiliated entities since 1986. Prior to being elected to the positions above, he was Controller of the various entities. From 1982 to 1986, Mr. Keene was with KPMG Certified Public Accountants, first as an auditor and later as a tax manager. Mr. Keene is responsible for all accounting functions of AFM and the registrant.

Since Mr. Johnson serves as the Individual General Partner of the Partnership, as well as the sole director of AFM, all of the duties that might be assigned to an audit committee are assigned to Mr. Johnson. Mr. Johnson is not an audit committee financial expert, as defined. As an officer and majority owner, through a parent company, of AFM, and as the Individual General Partner, Mr. Johnson is not a "disinterested director" and may be subject to a number of conflicts of interests in his capacity as sole director of AFM.

Before the independent auditors are engaged, Mr. Johnson, as the sole director of AFM, approves all audit-related fees, and all permissible nonaudit fees, for services of our auditors.

Section 16(a) Beneficial Ownership Reporting Compliance

Under federal securities laws, the directors and officers of the General Partner of the Partnership, and any beneficial owner of more than 10% of a class of equity securities of the Partnership, are required to report their ownership of the Partnership's equity securities and any changes in such ownership to the Securities and Exchange Commission (the "Commission"). Specific due dates for these reports have been established by the Commission, and the Partnership is required to disclose in this Annual Report on 10-K any delinquent filing of such reports and any failure to file such reports during the fiscal year ended December 31, 2012. Based upon information provided by officers and directors of the General Partner, all officers, directors and 10% owners filed all reports on a timely basis in the 2012 fiscal year.

Page 31 of 36

ITEM 11. EXECUTIVE COMPENSATION.

The General Partner and affiliates are reimbursed at cost for all services performed on behalf of the registrant and for all third party expenses paid on behalf of the registrant. The cost for services performed on behalf of the registrant is based on actual time spent performing such services plus an overhead burden. These services include organizing the registrant and arranging for the offer and sale of Units, reviewing properties for acquisition and rendering administrative, property management and property sales services. The amount and nature of such payments are detailed in Item 13 of this annual report on Form 10-K.

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND

MANAGEMENT AND RELATED STOCKHOLDER MATTERS.

The following table sets forth information pertaining to the ownership of the Units by each person known by the Partnership to beneficially own 5% or more of the Units, by each General Partner, and by each officer or director of the Managing General Partner as of February 28, 2013:

Name and Address of Beneficial Owner	Number of Units Held	Percent of Class

AEI Fund Management XXI, Inc.	0	0.00%
Robert P. Johnson	0	0.00%
Patrick W. Keene	0	0.00%

Address for all:
1300 Wells Fargo Place 30 East 7th Street, St. Paul, Minnesota 55101

The General Partners know of no holders of more than 5% of the outstanding Units.

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND

DIRECTOR INDEPENDENCE.

The registrant, AFM and its affiliates have common management and utilize the same facilities. As a result, certain administrative expenses are allocated among these related entities. All of such activities and any other transactions involving the affiliates of the General Partner of the registrant are governed by, and are conducted in conformity with, the limitations set forth in the Limited Partnership Agreement of the registrant. Reference is made to Note 3 of the Financial Statements, as presented, and is incorporated herein by reference, for details of related party transactions for the years ended December 31, 2012 and 2011.

Neither the registrant, nor the Managing General Partner of the registrant, has a board of directors consisting of any members who are “independent.” The sole director of the Managing General Partner, Robert P. Johnson, is also the Individual General Partner of the registrant, and is the Chief Executive Officer, and indirectly the principal owner, of the Managing General Partner. Accordingly, there is no disinterested board, or other functioning body, that reviews related party transactions, or the transactions between the registrant and the General Partners, except as performed in connection with the audit of its financial statements.

Page 32 of 36

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND

DIRECTOR INDEPENDENCE. (Continued)

The limitations included in the Partnership Agreement require that the cumulative reimbursements to the General Partners and their affiliates for certain expenses will not exceed an amount equal to the sum of (i) 20% of gross offering proceeds, (ii) 5% of Net Cash Flow for property management, (iii) 3% of Net Proceeds of Sale, and (iv) 10% of Net Cash Flow less the Net Cash Flow actually distributed to the General Partners. The cumulative reimbursements subject to this limitation are reimbursements for (i) organization and offering expenses, including commissions, (ii) acquisition expenses, (iii) services provided in the sales effort of properties, and (iv) expenses of controlling persons and overhead expenses directly attributable to the forgoing services or attributable to administrative services. As of December 31, 2012, these cumulative reimbursements to the General Partners and their affiliates did not exceed the limitation amount.

The following table sets forth the forms of compensation, distributions and cost reimbursements paid by the registrant to the General Partners or their Affiliates in connection with the operation of the Fund and its properties for the period from inception through December 31, 2012.

Person or Entity Receiving Compensation	Form and Method of Compensation	Amount Incurred From Inception (August 22, 1994) To December 31, 2012

AEI Securities, Inc.	Selling Commissions equal to 8% of proceeds plus a 2% nonaccountable expense allowance, most of which was reallowed to Participating Dealers.		$	2,400,000

General Partners and Affiliates	Reimbursement at Cost for other Organization and Offering Costs.		$	877,000

General Partners and Affiliates	Reimbursement at Cost for all Acquisition Expenses.		$	743,758

General Partners and Affiliates	Reimbursement at Cost for providing administrative services to the Fund, including all expenses related to management of the Fund's properties and all other transfer agency, reporting, partner relations and other administrative functions.		$	4,172,649

General Partners and Affiliates	Reimbursement at Cost for providing services related to the disposition of the Fund's properties.		$	1,160,184

General Partners	1% of Net Cash Flow in any fiscal year until the Limited Partners have received annual, non-cumulative distributions of Net Cash Flow equal to 10% of their Adjusted Capital Contributions and 10% of any remaining Net Cash Flow in such fiscal year.		$	236,210

Page 33 of 36

ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS, AND

DIRECTOR INDEPENDENCE. (Continued)

Person or Entity Receiving Compensation	Form and Method of Compensation	Amount Incurred From Inception (August 22, 1994) To December 31, 2012

General Partners	1% of distributions of Net Proceeds of Sale until Limited Partners have received an amount equal to (a) their Adjusted Capital Contributions, plus (b) an amount equal to 12% of their Adjusted Capital Contributions per annum, cumulative but not compounded, to the extent not previously distributed. 10% of distributions of Net Proceeds of Sale thereafter.		$	63,394

ITEM 14. PRINCIPAL ACCOUNTING FEES AND SERVICES.

The following is a summary of the fees billed to the Partnership by Boulay, Heutmaker, Zibell & Co. P.L.L.P. for professional services rendered for the years ended December 31, 2012 and 2011:

Fee Category		2012		2011

Audit Fees	$	17,109	$	16,861
Audit-Related Fees		0		0
Tax Fees		0		0
All Other Fees		0		0
Total Fees	$	17,109	$	16,861

Audit Fees - Consists of fees billed for professional services rendered for the audit of the Partnership’s annual financial statements and review of the interim financial statements included in quarterly reports, and services that are normally provided by Boulay, Heutmaker, Zibell & Co. P.L.L.P. in connection with statutory and regulatory filings or engagements.

Audit-Related Fees - Consists of fees billed for assurance and related services that are reasonably related to the performance of the audit or review of financial statements and are not reported under "Audit Fees." These services include consultations concerning financial accounting and reporting standards.

Tax Fees - Consists of fees billed for professional services for federal and state tax compliance, tax advice and tax planning.

All Other Fees - Consists of fees for products and services other than the services reported above.

Policy for Preapproval of Audit and Permissible Non-Audit Services of Independent Auditors

Before the Independent Auditors are engaged by the Partnership to render audit or non-audit services, the engagement is approved by Mr. Johnson acting as the Partnership’s audit committee.

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PART IV

ITEM 15. EXHIBITS, FINANCIAL STATEMENT SCHEDULES.

(a) (1) A list of the financial statements contained herein is set forth on page 13.

(a) (2) Schedules are omitted because of the absence of conditions under which they are required or because the required information is presented in the financial statements or related notes.

(a) (3) The Exhibits filed in response to Item 601 of Regulation S-K are listed below.

3.1	Certificate of Limited Partnership (incorporated by reference to Exhibit 3.1 of the registrant's Registration Statement on Form SB-2 filed October 10, 1994 [File No. 33-85076C]).

3.2	Restated Limited Partnership Agreement to the Prospectus (incorporated by reference to Exhibit A of Amendment No. 2 of the registrant's Registration Statement on Form SB-2 filed January 20, 1995 [File No. 33-85076C]).

10.1	Net Lease Agreement dated June 14, 2002 between the Partnership and ARAMARK Educational Resources, Inc. relating to the Property at 1485 Bunker Lake Boulevard NW, Andover, Minnesota (incorporated by reference to Exhibit 10.4 of Form 8-K filed June 27, 2002).

10.2

Assignment and Assumption of Lease dated February 9, 2004 between the Partnership, AEI Net Lease Income & Growth Fund XX Limited Partnership and Transmills, LLC relating to the Property at 7684 Arundel Mills, Hanover, Maryland (incorporated by reference to Exhibit 10.2 of Form 8-K filed February 24, 2004).

10.3	Assignment and Assumption of Lease dated January 14, 2005 between the Partnership, AEI Income & Growth Fund 25 LLC and LMB Auburn Hills I LLC relating to the Property at 3960 Baldwin Road, Auburn Hills, Michigan (incorporated by reference to Exhibit 10.26 of Form 10-KSB filed March 30, 2005).

10.4

Assignment and Assumption of Lease dated March 18, 2005 between the Partnership, AEI Income & Growth Fund 24 LLC, AEI Income & Growth Fund 25 LLC, AEI Private Net Lease Millennium Fund Limited Partnership and Silver Capital Net Lease Fund II, LLC relating to the Property at 1977 Thornton Road, Lithia Springs, Georgia (incorporated by reference to Exhibit 10.28 of Form 10-KSB filed March 30, 2005).

10.5	Net Lease Agreement dated September 21, 2006 between the Partnership, AEI Income & Growth Fund XXII Limited Partnership and B.T. Woodlipp, Inc. relating to the Property at 425 Galleria Drive, Johnstown, Pennsylvania (incorporated by reference to Exhibit 10.2 of Form 10-QSB filed November 14, 2006).

10.6

Assignment and Assumption of Lease dated January 31, 2008 between the Partnership, AEI Income & Growth Fund 23 LLC, AEI Income & Growth Fund 26 LLC and Eau Claire Equity Fund Limited Partnership relating to the Property at 4090 Commonwealth Avenue, Eau Claire, Wisconsin (incorporated by reference to Exhibit 10.2 of Form 8-K filed February 6, 2008).

31.1	Certification of Chief Executive Officer of General Partner pursuant to Rule 15d-14(a)(17 CFR 240.15d-14(a)) and Section 302 of the Sarbanes-Oxley Act of 2002.

31.2	Certification of Chief Financial Officer of General Partner pursuant to Rule 15d-14(a)(17 CFR 240.15d-14(a)) and Section 302 of the Sarbanes-Oxley Act of 2002.

32	Certification of Chief Executive Officer and Chief Financial Officer of General Partner pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

Page 35 of 36

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	AEI INCOME & GROWTH FUND XXI
	Limited Partnership
	By:	AEI Fund Management XXI, Inc.
		Its Managing General Partner


March 29, 2013	By:	/s/ ROBERT P JOHNSON
		Robert P. Johnson, President and Director
		(Principal Executive Officer)

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Name	Title	Date


/s/ ROBERT P JOHNSON	President (Principal Executive Officer)	March 29, 2013
Robert P. Johnson	and Sole Director of Managing General
	Partner

/s/ PATRICK W KEENE	Chief Financial Officer and Treasurer	March 29, 2013
Patrick W. Keene	(Principal Accounting Officer)

Page 36 of 36

Discontinued Operations (Detail) (USD $)	12 Months Ended		0 Months Ended		6 Months Ended	12 Months Ended		0 Months Ended
Discontinued Operations (Detail) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Jan. 19, 2011 Chammps Livonia MI	Mar. 25, 2011 KinderCare Ballwin MO	Dec. 31, 2011 Winn Dixie Panama City FL 2011	Dec. 31, 2012 Winn Dixie Panama City FL	Dec. 31, 2011 Winn Dixie Panama City FL	Feb. 03, 2012 Arby's Montgomery AL
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds			$ 7,861	$ 902,133	$ 547,411	$ 406,884		$ 16,200
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax			3,904	362,374	101,088	68,108		1,788
Real Estate, Cost of Real Estate Sold			6,366	675,587	537,605	408,060		23,049
Real Estate Accumulated Depreciation, Real Estate Sold			2,409	135,828	91,282	69,284		8,637
Disposal Group, Including Discontinued Operation, Property, Plant, and Equipment, Net							338,776
Distribution Of Net Sale Proceeds	$ 94,675	$ 41,554
Return Of Capital Distribution Made To Member Or Limited Partner Distributions Paid Per Unit (in Dollars per share)	$ 4.14	$ 1.81

Partners' Capital (Detail) (USD $)	12 Months Ended
Partners' Capital (Detail) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Apr. 14, 1995
Partners' Capital Account, Distributions	$ 1,175,746	$ 1,175,750
Limited Partner [Member]
Distribution Made to Member or Limited Partner, Cash Distributions Paid	1,163,988	1,163,992
Distributions Per Limited Partnership Unit Outstanding, Basic (in Dollars per share)	$ 51.37	$ 51.34
Weighted Average Limited Partnership Units Outstanding, Basic (in Shares)	22,661	22,671
DistributionsPerUnitOfNetIncome (in Dollars per Item)	28.78	48.36
DistributionsPerUnitOfReturnOfCapital (in Dollars per Item)	22.59	2.98
Sale Proceeds Distribution Made To Member Or Limited Partner	93,728	41,138
Partners' Capital Account, Units, Redeemed (in Shares)	10.00	10.50
Limited Partner Capital Accounts Redemptions	2,607	3,127
GeneralPartnerDistributionsFromRedemptions	27	32
AdjustedCapitalContributionsPerPartnershipAgreement	1,059.46
Capital Units, Value			1,000
General Partner [Member]
General Partners' Capital Account, Period Distribution Amount	$ 11,758	$ 11,758

Summary of Significant Accounting Policies (Detail)	12 Months Ended
Summary of Significant Accounting Policies (Detail)	Dec. 31, 2012
Building and Building Improvements [Member]
Property, Plant and Equipment, Useful Life	25 years
Furniture and Fixtures [Member]
Property, Plant and Equipment, Useful Life	5 years

Related Party Transactions (Detail) - Related Party Transactions (Parentheticals) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Partnership Administration - Affiliates - Discontinued Operations	$ 1,150	$ 2,302

Document And Entity Information (USD $)	12 Months Ended
Document And Entity Information (USD $)	Dec. 31, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	AEI Income & Growth Fund XXI Ltd Partnership
Document Type	10-K
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding	22,663
Entity Public Float	$ 0
Amendment Flag	false
Entity Central Index Key	0000931755
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Well-known Seasoned Issuer	No
Document Period End Date	Dec. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q4

Date: March 29, 2013	/s/ ROBERT P JOHNSON
	Robert P. Johnson, President
	AEI Fund Management XXI, Inc.
	Managing General Partner

Date: March 29, 2013	/s/ PATRICK W KEENE
	Patrick W. Keene, Chief Financial Officer
	AEI Fund Management XXI, Inc.
	Managing General Partner

Real Estate Held for Investment (Detail) - Real Estate Held for Investment (USD $)	Dec. 31, 2012	Dec. 31, 2011
Land	$ 4,403,667
Buildings and Equipment	12,273,366
Total	16,677,033
Accumulated Depreciation	2,930,639	2,448,341
KinderCare Andover MN
Land	179,755
Buildings and Equipment	1,084,452
Total	1,264,207
Accumulated Depreciation	457,276
Jared Jewelry Hanover MD
Land	861,065
Buildings and Equipment	1,128,070
Total	1,989,135
Accumulated Depreciation	400,466
Jared Jewelry Auburn Hills MI
Land	280,993
Buildings and Equipment	1,185,055
Total	1,466,048
Accumulated Depreciation	377,241
CarMax Lithia Springs GA
Land	815,180
Buildings and Equipment	1,070,051
Total	1,885,231
Accumulated Depreciation	333,499
Applebees Johnstown PA
Land	431,754
Buildings and Equipment	1,251,133
Total	1,682,887
Accumulated Depreciation	314,867
Best Buy Eau Claire WI
Land	853,357
Buildings and Equipment	2,784,349
Total	3,637,706
Accumulated Depreciation	547,589
Fresenius Medical Center Shreveport LA
Land	102,046
Buildings and Equipment	1,258,571
Total	1,360,617
Accumulated Depreciation	213,958
Tractor Supply Rapid City SD
Land	588,967
Buildings and Equipment	1,368,767
Total	1,957,734
Accumulated Depreciation	184,785
Scott White College Station TX
Land	290,550
Buildings and Equipment	1,142,918
Total	1,433,468
Accumulated Depreciation	$ 100,958

Balance Sheet (USD $)	Dec. 31, 2012	Dec. 31, 2011
Current Assets:
Cash	$ 2,259,911	$ 1,934,854
Real Estate Held for Investment:
Land	4,403,667	4,413,700
Buildings and Equipment	12,273,366	12,286,382
Accumulated Depreciation	2,930,639	2,448,341
Real Estate Held for Investment, Net	13,746,394	14,251,741
Real Estate Held for Sale	0	338,776
Total Real Estate	13,746,394	14,590,517
Total Assets	16,006,305	16,525,371
Current Liabilities:
Payable to AEI Fund Management, Inc.	41,189	34,777
Distributions Payable	293,940	293,935
Unearned Rent	12,120	21,889
Total Current Liabilities	347,249	350,601
Partners’ Capital:
General Partners	686	4,646
Limited Partners – 24,000 Units authorized; 22,653 and 22,663 Units issued and outstanding in 2012 and 2011, respectively	15,658,370	16,170,124
Total Partners' Capital	15,659,056	16,174,770
Total Liabilities and Partners' Capital	$ 16,006,305	$ 16,525,371

Statement of Changes in Partners' Capital (USD $)	General Partner [Member]	Limited Partner [Member]	Total
Balance at Dec. 31, 2010	$ 2,613	$ 16,237,802	$ 16,240,415
Balance (in Shares) at Dec. 31, 2010		22,673.61
Distributions Declared	11,758	1,163,992	1,175,750
Redemptions Payments	32	3,127	3,159
Units Redeemed (in Shares)		10.50
Net Income	13,823	1,099,441	1,113,264
Balance at Dec. 31, 2011	4,646	16,170,124	16,174,770
Balance (in Shares) at Dec. 31, 2011		22,663.11	22,663
Distributions Declared	11,758	1,163,988	1,175,746
Redemptions Payments	27	2,607	2,634
Units Redeemed (in Shares)		10.00
Net Income	7,825	654,841	662,666
Balance at Dec. 31, 2012	$ 686	$ 15,658,370	$ 15,659,056
Balance (in Shares) at Dec. 31, 2012		22,653.11	22,663

Balance Sheet (Parentheticals)	Dec. 31, 2012	Dec. 31, 2011
Limited Partners, unit authorized	24,000	24,000
Limited Partners, units issued	22,653	22,663
Limited Partners, units outstanding	22,663	22,663

Statement of Income (USD $)	12 Months Ended
Statement of Income (USD $)	Dec. 31, 2012	Dec. 31, 2011
Rental Income	$ 1,334,130	$ 1,309,549
Expenses:
Partnership Administration – Affiliates	212,740	227,579
Partnership Administration and Property Management – Unrelated Parties	64,487	38,889
Depreciation	490,935	490,935
Total Expenses	768,162	757,403
Operating Income	565,968	552,146
Other Income:
Interest Income	7,723	7,654
Income from Continuing Operations	573,691	559,800
Income from Discontinued Operations	88,975	553,464
Net Income	662,666	1,113,264
Net Income Allocated:
General Partners	7,825	13,823
Limited Partners	654,841	1,099,441
Total	$ 662,666	$ 1,113,264
Income per Limited Partnership Unit:
Continuing Operations (in Dollars per Item)	25.06	24.45
Discontinued Operations (in Dollars per Item)	3.84	24.05
Total – Basic and Diluted (in Dollars per Item)	28.90	48.50
Weighted Average Units Outstanding – Basic and Diluted (in Shares)	22,661	22,671

Accounting Policies, by Policy (Policies)	12 Months Ended
Accounting Policies, by Policy (Policies)	Dec. 31, 2012
Distribution Policy, Members or Limited Partners, Description	During operations, any Net Cash Flow, as defined, which the General Partners determine to distribute will be distributed 90% to the Limited Partners and 10% to the General Partners; provided, however, that such distributions to the General Partners will be subordinated to the Limited Partners first receiving an annual, noncumulative distribution of Net Cash Flow equal to 10% of their Adjusted Capital Contribution, as defined, and, provided further, that in no event will the General Partners receive less than 1% of such Net Cash Flow per annum. Distributions to Limited Partners will be made pro rata by Units. Any Net Proceeds of Sale, as defined, from the sale or financing of properties which the General Partners determine to distribute will, after provisions for debts and reserves, be paid in the following manner: (i) first, 99% to the Limited Partners and 1% to the General Partners until the Limited Partners receive an amount equal to: (a) their Adjusted Capital Contribution plus (b) an amount equal to 10% of their Adjusted Capital Contribution per annum, cumulative but not compounded, to the extent not previously distributed from Net Cash Flow; (ii) any remaining balance will be distributed 90% to the Limited Partners and 10% to the General Partners. Distributions to the Limited Partners will be made pro rata by Units.
Key Provisions of Operating or Partnership Agreement, Description	Any Net Proceeds of Sale, as defined, from the sale or financing of properties which the General Partners determine to distribute will, after provisions for debts and reserves, be paid in the following manner: (i) first, 99% to the Limited Partners and 1% to the General Partners until the Limited Partners receive an amount equal to: (a) their Adjusted Capital Contribution plus (b) an amount equal to 10% of their Adjusted Capital Contribution per annum, cumulative but not compounded, to the extent not previously distributed from Net Cash Flow; (ii) any remaining balance will be distributed 90% to the Limited Partners and 10% to the General Partners. Distributions to the Limited Partners will be made pro rata by Units. For tax purposes, profits from operations, other than profits attributable to the sale, exchange, financing, refinancing or other disposition of property, will be allocated first in the same ratio in which, and to the extent, Net Cash Flow is distributed to the Partners for such year. Any additional profits will be allocated in the same ratio as the last dollar of Net Cash Flow is distributed. Net losses from operations will be allocated 99% to the Limited Partners and 1% to the General Partners. For tax purposes, profits arising from the sale, financing, or other disposition of property will be allocated in accordance with the Partnership Agreement as follows: (i) first, to those partners with deficit balances in their capital accounts in an amount equal to the sum of such deficit balances; (ii) second, 99% to the Limited Partners and 1% to the General Partners until the aggregate balance in the Limited Partners' capital accounts equals the sum of the Limited Partners' Adjusted Capital Contributions plus an amount equal to 10% of their Adjusted Capital Contributions per annum, cumulative but not compounded, to the extent not previously allocated; (iii) third, the balance of any remaining gain will then be allocated 90% to the Limited Partners and 10% to the General Partners. Losses will be allocated 98% to the Limited Partners and 2% to the General Partners. The General Partners are not required to currently fund a deficit capital balance. Upon liquidation of the Partnership or withdrawal by a General Partner, the General Partners will contribute to the Partnership an amount equal to the lesser of the deficit balances in their capital accounts or 1% of total Limited Partners' and General Partners' capital contributions.
Basis of Accounting, Policy [Policy Text Block]	Financial Statement Presentation The accounts of the Partnership are maintained on the accrual basis of accounting for both federal income tax purposes and financial reporting purposes.
Use of Estimates, Policy [Policy Text Block]	Accounting Estimates Management uses estimates and assumptions in preparing these financial statements in accordance with generally accepted accounting principles. Those estimates and assumptions may affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported revenues and expenses. Actual results could differ from those estimates. Significant items, subject to such estimates and assumptions, include the carrying value of real estate held for investment and real estate held for sale. The Partnership regularly assesses whether market events and conditions indicate that it is reasonably possible to recover the carrying amounts of its investments in real estate from future operations and sales. A change in those market events and conditions could have a material effect on the carrying amount of its real estate.
Concentration Risk, Credit Risk, Policy [Policy Text Block]	Cash Concentrations of Credit Risk The Partnership's cash is deposited in one financial institution and at times during the year it may exceed FDIC insurance limits.
Receivables, Policy [Policy Text Block]	Receivables Credit terms are extended to tenants in the normal course of business. The Partnership performs ongoing credit evaluations of its customers’ financial condition and, generally, requires no collateral. Receivables are recorded at their estimated net realizable value. The Partnership follows a policy of providing an allowance for doubtful accounts; however, based on historical experience, and its evaluation of the current status of receivables, the Partnership is of the belief that such accounts, if any, will be collectible in all material respects and thus an allowance is not necessary. Accounts are considered past due if payment is not made on a timely basis in accordance with the Partnership’s credit terms. Receivables considered uncollectible are written off.
Income Tax, Policy [Policy Text Block]	Income Taxes The income or loss of the Partnership for federal income tax reporting purposes is includable in the income tax returns of the partners. In general, no recognition has been given to income taxes in the accompanying financial statements. The tax return and the amount of distributable Partnership income or loss are subject to examination by federal and state taxing authorities. If such an examination results in changes to distributable Partnership income or loss, the taxable income of the partners would be adjusted accordingly. Primarily due to its tax status as a partnership, the Partnership has no significant tax uncertainties that require recognition or disclosure. The Partnership is no longer subject to U.S. federal income tax examinations for tax years before 2009, and with few exceptions, is no longer subject to state tax examinations for tax years before 2009.
Revenue Recognition Leases [Policy Text Block]	Revenue Recognition The Partnership's real estate is leased under net leases, classified as operating leases. The leases provide for base annual rental payments payable in monthly installments. The Partnership recognizes rental revenue according to the terms of the individual leases. For leases that contain stated rental increases, the increases are recognized in the year in which they are effective. Contingent rental payments are recognized when the contingencies on which the payments are based are satisfied and the rental payments become due under the terms of the leases.
Property, Plant and Equipment, Policy [Policy Text Block]	Real Estate The Partnership purchases properties and records them at cost. The Partnership tests real estate for recoverability when events or changes in circumstances indicate that the carrying value may not be recoverable. For properties the Partnership will hold and operate, it compares the carrying amount of the property to the estimated probability-weighted future undiscounted cash flows expected to result from the property and its eventual disposition. If the sum of the expected future cash flows is less than the carrying amount of the property, the Partnership recognizes an impairment loss by the amount by which the carrying amount of the property exceeds the fair value of the property. For properties held for sale, the Partnership determines whether impairment has occurred by comparing the property’s estimated fair value less cost to sell to its current carrying value. If the carrying value is greater than the net realizable value, an impairment loss is recorded to reduce the carrying value of the property to its net realizable value. The buildings and equipment of the Partnership are depreciated using the straight-line method for financial reporting purposes based on estimated useful lives of 25 years and 5 years, respectively. Upon complete disposal of a property or classification of a property as Real Estate Held for Sale, the Partnership includes the operating results and sale of the property in discontinued operations. In addition, the Partnership reclassifies the prior periods’ operating results of the property to discontinued operations. The Partnership accounts for properties owned as tenants-in-common with affiliated entities and/or unrelated third parties using the proportionate consolidation method. Each tenant-in-common owns a separate, undivided interest in the properties. Any tenant-in-common that holds more than a 50% interest does not control decisions over the other tenant-in-common interests. The financial statements reflect only this Partnership's percentage share of the properties' land, building and equipment, liabilities, revenues and expenses. The Partnership’s properties are subject to environmental laws and regulations adopted by various governmental entities in the jurisdiction in which the properties are located. These laws could require the Partnership to investigate and remediate the effects of the release or disposal of hazardous materials at these locations if found. For each property, an environmental assessment is completed prior to acquisition. In addition, the lease agreements typically strictly prohibit the production, handling, or storage of hazardous materials (except where incidental to the tenant’s business such as use of cleaning supplies) in violation of applicable law to restrict environmental and other damage. Environmental liabilities are recorded when it is determined the liability is probable and the costs can reasonably be estimated. There were no environmental issues noted or liabilities recorded at December 31, 2012 and 2011.
Fair Value of Financial Instruments, Policy [Policy Text Block]	Fair Value Measurements As of December 31, 2012, the Partnership had no assets or liabilities measured at fair value on a recurring basis or nonrecurring basis.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Pronouncements Management has reviewed recently issued, but not yet effective, accounting pronouncements and does not expect the implementation of these pronouncements to have a significant effect on the Partnership’s financial statements.
Reclassification, Policy [Policy Text Block]	Reclassification Certain items related to discontinued operations in the prior year’s financial statements have been reclassified to conform to 2012 presentation. These reclassifications had no effect on Partners’ capital, net income or cash flows.

Organization (Detail) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 31, 1997	Apr. 14, 1995
Limited Partners' Capital Account, Units Outstanding (in Shares)	22,663	22,663
Limited Partner [Member]
Capital Units, Value					$ 1,000
Limited Partners' Capital Account, Units Outstanding (in Shares)	22,653.11	22,663.11	22,673.61	24,000	1,500
Limited Partners' Contributed Capital				24,000,000	1,500,000
General Partner [Member]
General Partners' Contributed Capital				$ 1,000

Real Estate Held for Investment (Detail) - Minimum Future Payments (USD $)	Dec. 31, 2012
2013	$ 1,358,017
2014	1,366,157
2015	1,386,254
2016	1,398,713
2017	1,345,950
Thereafter	3,874,323
	$ 10,729,414

Statement of Cash Flows (USD $)	12 Months Ended
Statement of Cash Flows (USD $)	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities:
Net Income	$ 662,666	$ 1,113,264
Adjustments to Reconcile Net Income To Net Cash Provided by Operating Activities:
Depreciation	490,935	491,456
Gain on Sale of Real Estate	69,896	467,366
Increase (Decrease) in Payable to AEI Fund Management, Inc.	6,412	10,250
Increase (Decrease) in Unearned Rent	(9,769)	(5,121)
Total Adjustments	417,682	29,219
Net Cash Provided By Operating Activities	1,080,348	1,142,483
Cash Flows from Investing Activities:
Proceeds from Sale of Real Estate	423,084	1,457,405
Cash Flows from Financing Activities:
Distributions Paid to Partners	1,175,741	1,176,764
Redemption Payments	2,634	3,159
Net Cash Used For Financing Activities	(1,178,375)	(1,179,923)
Net Increase (Decrease) in Cash	325,057	1,419,965
Cash, beginning of year	1,934,854	514,889
Cash, end of year	$ 2,259,911	$ 1,934,854

Major Tenants (Detail) - Major Tenants (USD $)	12 Months Ended
Major Tenants (Detail) - Major Tenants (USD $)	Dec. 31, 2012	Dec. 31, 2011
Major Tenants	$ 981,050	$ 979,607
Aggregate rent revenue of major tenants as a percentage of total rent revenue	72.00%	70.00%
Sterling Jewelers Inc
Major Tenants	298,178	286,707
Best Buy Stores LP
Major Tenants	256,000	256,001
CarMax Auto Superstores Inc
Major Tenants	146,286	146,612
Tractor Supply Company
Major Tenants	141,750	141,750
KinderCare Learning Centers LLC
Major Tenants	$ 138,836	$ 148,537