N-CSRS 1 a08-14616_12ncsrs.htm N-CSRS

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number			811-10597

Tax-Managed Mid-Cap Core Portfolio
(Exact name of registrant as specified in charter)

The Eaton Vance Building, 255 State Street, Boston, Massachusetts					02109
(Address of principal executive offices)					(Zip code)

Maureen A. Gemma The Eaton Vance Building, 255 State Street, Boston, Massachusetts 02109
(Name and address of agent for service)

Registrant’s telephone number, including area code:				(617) 482-8260

Date of fiscal year end:	October 31

Date of reporting period:		April 30, 2008

Item 1. Reports to Stockholders

Tax-Managed Mid-Cap Core Portfolio as of April 30, 2008

PORTFOLIO OF INVESTMENTS (Unaudited)

Common Stocks — 99.3%
Security	Shares		Value
Air Freight & Logistics — 1.8%
CH Robinson Worldwide, Inc.		18,200	$	1,140,776
Expeditors International of Washington, Inc.		13,300		619,647
			$	1,760,423
Airlines — 0.8%
SkyWest, Inc.		40,000	$	761,200
			$	761,200
Auto Components — 2.0%
BorgWarner, Inc.		40,000	$	1,966,000
			$	1,966,000
Automobiles — 1.1%
Thor Industries, Inc.		35,000	$	1,061,200
			$	1,061,200
Capital Markets — 5.3%
Affiliated Managers Group, Inc.⁽¹⁾		18,800	$	1,867,592
Federated Investors, Inc., Class B		27,000		903,960
Raymond James Financial, Inc.		50,000		1,438,500
SEI Investments Co.		44,600		1,037,842
			$	5,247,894
Chemicals — 2.6%
Albemarle Corp.		35,200	$	1,316,832
RPM International, Inc.		56,000		1,248,800
			$	2,565,632
Commercial Banks — 4.2%
City National Corp.		22,000	$	1,067,440
Cullen/Frost Bankers, Inc.		35,700		1,992,774
Westamerica Bancorporation		18,000		1,051,920
			$	4,112,134
Commercial Services & Supplies — 1.8%
FTI Consulting, Inc.⁽¹⁾		27,000	$	1,728,000
			$	1,728,000

Security	Shares		Value
Computer Peripherals — 0.4%
Diebold, Inc.		10,000	$	392,000
			$	392,000
Construction & Engineering — 2.3%
Jacobs Engineering Group, Inc.⁽¹⁾		26,000	$	2,244,580
			$	2,244,580
Construction Materials — 1.2%
Martin Marietta Materials, Inc.		11,000	$	1,203,180
			$	1,203,180
Containers & Packaging — 1.7%
Sonoco Products Co.		51,300	$	1,690,335
			$	1,690,335
Electric Utilities — 1.6%
DPL, Inc.		56,600	$	1,575,178
			$	1,575,178
Electrical Equipment — 2.1%
AMETEK, Inc.		42,000	$	2,037,840
			$	2,037,840
Electronic Equipment & Instruments — 3.8%
Amphenol Corp., Class A		46,000	$	2,124,280
National Instruments Corp.		55,000		1,618,100
			$	3,742,380
Energy Equipment & Services — 4.0%
FMC Technologies, Inc.⁽¹⁾		47,000	$	3,158,400
Helmerich & Payne, Inc.		14,000		752,500
			$	3,910,900
Food & Staples Retailing — 1.4%
Ruddick Corp.		36,000	$	1,393,200
			$	1,393,200

See notes to financial statements
15

Tax-Managed Mid-Cap Core Portfolio as of April 30, 2008

PORTFOLIO OF INVESTMENTS (Unaudited) CONT'D

Security	Shares		Value
Food Products — 1.8%
Corn Products International, Inc.		16,000	$	742,080
Hormel Foods Corp.		26,000		1,024,660
			$	1,766,740
Gas Utilities — 4.4%
AGL Resources, Inc.		41,100	$	1,397,400
Energen Corp.		20,000		1,364,800
Questar Corp.		26,000		1,612,780
			$	4,374,980
Health Care Equipment & Supplies — 6.8%
Bard (C.R.), Inc.		15,800	$	1,487,886
Beckman Coulter, Inc.		18,400		1,256,720
DENTSPLY International, Inc.		37,800		1,469,286
Mentor Corp.		31,000		907,370
Varian Medical Systems, Inc.⁽¹⁾		33,500		1,570,480
			$	6,691,742
Health Care Providers & Services — 4.4%
Henry Schein, Inc.⁽¹⁾		25,000	$	1,384,250
Owens & Minor, Inc.		38,000		1,722,160
Patterson Cos., Inc.⁽¹⁾		35,000		1,197,000
			$	4,303,410
Hotels, Restaurants & Leisure — 1.4%
Sonic Corp.⁽¹⁾		63,850	$	1,404,062
			$	1,404,062
Household Durables — 1.0%
Mohawk Industries, Inc.⁽¹⁾		13,000	$	990,470
			$	990,470
Insurance — 5.3%
Brown and Brown, Inc.		55,000	$	1,056,000
HCC Insurance Holdings, Inc.		73,000		1,801,640
Markel Corp.⁽¹⁾		2,300		999,120
Protective Life Corp.		31,000		1,321,220
			$	5,177,980

Security	Shares		Value
IT Services — 1.0%
Fiserv, Inc.⁽¹⁾		20,200	$	1,021,110
			$	1,021,110
Life Sciences Tools & Services — 1.1%
Pharmaceutical Product Development, Inc.		26,000	$	1,076,920
			$	1,076,920
Machinery — 5.5%
Donaldson Co., Inc.		40,000	$	1,741,600
Graco, Inc.		45,200		1,871,732
IDEX Corp.		50,000		1,834,500
			$	5,447,832
Metals & Mining — 1.8%
Reliance Steel & Aluminum Co.		29,000	$	1,762,620
			$	1,762,620
Multiline Retail — 1.6%
Dollar Tree, Inc.⁽¹⁾		50,000	$	1,580,000
			$	1,580,000
Multi-Utilities — 2.7%
NSTAR		40,000	$	1,288,400
OGE Energy Corp.		42,300		1,382,787
			$	2,671,187
Office Electronics — 1.4%
Zebra Technologies Corp., Class A⁽¹⁾		36,275	$	1,333,106
			$	1,333,106
Oil, Gas & Consumable Fuels — 4.3%
Holly Corp.		35,000	$	1,451,800
Peabody Energy Corp.		20,000		1,222,600
Plains Exploration & Production Co.⁽¹⁾		25,805		1,607,135
			$	4,281,535
Personal Products — 1.8%
Alberto-Culver Co.		72,000	$	1,812,240
			$	1,812,240

See notes to financial statements
16

Tax-Managed Mid-Cap Core Portfolio as of April 30, 2008

PORTFOLIO OF INVESTMENTS (Unaudited) CONT'D

Security	Shares		Value
Real Estate Investment Trusts (REITs) — 1.1%
Health Care REIT, Inc.		22,000	$	1,065,900
			$	1,065,900
Semiconductors & Semiconductor Equipment — 2.1%
Microchip Technology, Inc.		57,050	$	2,096,588
			$	2,096,588
Software — 5.7%
ANSYS, Inc.⁽¹⁾		42,200	$	1,697,706
Citrix Systems, Inc.⁽¹⁾		27,500		900,625
Fair Isaac Corp.		40,000		990,800
Jack Henry & Associates, Inc.		78,500		2,062,980
			$	5,652,111
Specialty Retail — 3.6%
O'Reilly Automotive, Inc.⁽¹⁾		70,000	$	2,020,900
Ross Stores, Inc.		44,500		1,490,305
			$	3,511,205
Tobacco — 0.9%
Universal Corp., VA		14,000	$	898,660
			$	898,660
Trading Companies & Distributors — 1.5%
MSC Industrial Direct Co., Inc., Class A		30,000	$	1,462,800
			$	1,462,800
Total Common Stocks (identified cost $75,847,377)			$	97,775,274
Total Investments — 99.3% (identified cost $75,847,377)			$	97,775,274
Other Assets, Less Liabilities — 0.7%			$	658,599
Net Assets — 100.0%			$	98,433,873

⁽¹⁾ Non-income producing security.

See notes to financial statements
17

Tax-Managed Mid-Cap Core Portfolio as of April 30, 2008

FINANCIAL STATEMENTS (Unaudited)

Statement of Assets and Liabilities

As of April 30, 2008

Assets
Investments, at value (identified cost, $75,847,377)	$	97,775,274
Cash		662,185
Dividends and interest receivable		92,794
Total assets	$	98,530,253
Liabilities
Payable to affiliate for investment adviser fee	$	63,998
Accrued expenses		32,382
Total liabilities	$	96,380
Net Assets applicable to investors' interest in Portfolio	$	98,433,873
Sources of Net Assets
Net proceeds from capital contributions and withdrawals	$	76,505,976
Net unrealized appreciation (computed on the basis of identified cost)		21,927,897
Total	$	98,433,873

Statement of Operations

For the Six Months Ended
April 30, 2008

Investment Income
Dividends	$	617,198
Interest		8,106
Total investment income	$	625,304
Expenses
Investment adviser fee	$	391,280
Trustees' fees and expenses		3,633
Custodian fee		41,294
Legal and accounting services		8,802
Miscellaneous		4,565
Total expenses	$	449,574
Deduct — Reduction of investment adviser fee	$	3,229
Total expense reductions	$	3,229
Net expenses	$	446,345
Net investment income	$	178,959
Realized and Unrealized Gain (Loss)
Net realized gain (loss) — Investment transactions (identified cost basis)	$	3,009,959
Net realized gain	$	3,009,959
Change in unrealized appreciation (depreciation) — Investments (identified cost basis)	$	(8,004,018	)
Net change in unrealized appreciation (depreciation)	$	(8,004,018	)
Net realized and unrealized loss	$	(4,994,059	)
Net decrease in net assets from operations	$	(4,815,100	)

See notes to financial statements
18

Tax-Managed Mid-Cap Core Portfolio as of April 30, 2008

FINANCIAL STATEMENTS CONT'D

Statements of Changes in Net Assets

Increase (Decrease) in Net Assets	Six Months Ended April 30, 2008 (Unaudited)			Year Ended October 31, 2007
From operations — Net investment income	$	178,959		$	431,454
Net realized gain from investment transactions		3,009,959			8,082,328
Net change in unrealized appreciation (depreciation) of investments		(8,004,018	)		8,326,667
Net increase (decrease) in net assets from operations	$	(4,815,100	)	$	16,840,449
Capital transactions — Contributions	$	2,410,474		$	8,454,067
Withdrawals		(9,326,108	)		(13,006,661	)
Net decrease in net assets from capital transactions	$	(6,915,634	)	$	(4,552,594	)
Net increase (decrease) in net assets	$	(11,730,734	)	$	12,287,855
Net Assets
At beginning of period	$	110,164,607		$	97,876,752
At end of period	$	98,433,873		$	110,164,607

See notes to financial statements
19

Tax-Managed Mid-Cap Core Portfolio as of April 30, 2008

FINANCIAL STATEMENTS CONT'D

Supplementary Data

	Six Months Ended April 30, 2008			Year Ended October 31,
	(Unaudited)			2007			2006			2005			2004			2003
Ratios/Supplemental Data
Ratios (As a percentage of average daily net assets):
Expenses⁽¹⁾		0.92	%⁽²⁾		0.90	%		0.91	%		0.91	%		0.93	%		0.99	%
Net investment income (loss)		0.37	%⁽²⁾		0.41	%		0.29	%		(0.11	)%		(0.15	)%		(0.22	)%
Portfolio Turnover		19	%		38	%		55	%		53	%		42	%		50	%
Total Return		(4.45	)%⁽³⁾		17.79	%		13.85	%		10.54	%		6.43	%		25.97	%
Net assets, end of period (000's omitted)	$	98,434		$	110,165		$	97,877		$	76,091		$	67,130		$	46,112

⁽¹⁾ The investment adviser waived a portion of its investment advisory fee (equal to less than 0.01% of average daily net assets for the six months ended April 30, 2008 and for each of the years ended October 31, 2007, 2006, 2005 and 2004). A portion of the waiver was borne by the sub-adviser.

⁽²⁾ Annualized.

⁽³⁾ Not annualized.

See notes to financial statements
20

Tax-Managed Mid-Cap Core Portfolio as of April 30, 2008

NOTES TO FINANCIAL STATEMENTS (Unaudited)

1 Significant Accounting Policies

Tax-Managed Mid-Cap Core Portfolio (the Portfolio) is a New York trust registered under the Investment Company Act of 1940, as amended (the 1940 Act), as a diversified, open-end management investment company. The Portfolio's investment objective is to achieve long-term, after-tax returns by investing in a diversified portfolio of common stocks of mid-cap companies. The Declaration of Trust permits the Trustees to issue interests in the Portfolio. At April 30, 2008, Eaton Vance Tax-Managed Mid-Cap Core Fund and Eaton Vance Tax-Managed Equity Asset Allocation Fund held an interest of 36.1% and 63.9%, respectively, in the Portfolio.

The following is a summary of significant accounting policies of the Portfolio. The policies are in conformity with accounting principles generally accepted in the United States of America.

A Investment Valuation — Equity securities listed on a U.S. securities exchange generally are valued at the last sale price on the day of valuation or, if no sales took place on such date, at the mean between the closing bid and asked prices therefore on the exchange where such securities are principally traded. Equity securities listed on the NASDAQ Global or Global Select Market generally are valued at the NASDAQ official closing price. Unlisted or listed securities for which closing sales prices or closing quotations are not available are valued at the mean between the latest available bid and asked prices or, in the case of preferred equity securities that are not listed or traded in the over-the-counter market, by an independent pricing service. Short-term debt securities with a remaining maturity of sixty days or less are valued at amortized cost, which approximates market value. If short-term debt securities are acquired with a remaining maturity of more than sixty days, they will be valued by a pricing service. Other fixed income and debt securities, including listed securities and securities for which price quotations are available, will normally be valued on the basis of valuations furnished by a pricing service. Investments for which valuations or market quotations are not readily available are valued at fair value using methods determined in good faith by or at the direction of the Trustees of the Portfolio considering relevant factors, data and information including the market value of freely tradable securities of the same class in the principal market on which such securities are normally traded.

B Investment Transactions — Investment transactions for financial statement purposes are accounted for on a trade date basis. Realized gains and losses on investments sold are determined on the basis of identified cost.

C Income — Dividend income is recorded on the ex-dividend date for dividends received in cash and/or securities. Interest income is recorded on the basis of interest accrued, adjusted for amortization of premium or accretion of discount.

D Federal Taxes — The Portfolio has elected to be treated as a partnership for federal tax purposes. No provision is made by the Portfolio for federal or state taxes on any taxable income of the Portfolio because each investor in the Portfolio is ultimately responsible for the payment of any taxes on its share of taxable income. Since at least one of the Portfolio's investors is a regulated investment company that invests all or substantially all of its assets in the Portfolio, the Portfolio normally must satisfy the applicable source of income and diversification requirements (under the Internal Revenue Code) in order for its investors to satisfy them. The Portfolio will allocate, at least annually among its investors, each investor's distributive share of the Portfolio's net investment income, net realized capital gains and any other items of income, gain, loss, deduction or credit.

In June 2006, the Financial Accounting Standards Board (FASB) issued FASB Interpretation No. 48 (FIN 48), "Accounting for Uncertainty in Income Taxes – an interpretation of FASB Statement No. 109". FIN 48 clarifies the accounting for uncertainty in income taxes recognized in accordance with FASB Statement No. 109, "Accounting for Income Taxes". This interpretation prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. It also provides guidance on de-recognition, classification, interest and penalties, accounting in interim periods, disclosure and transition. FIN 48 is effective on the last business day of the first required financial reporting period for fiscal years beginning after December 15, 2006. Management has concluded that as of April 30, 2008, there are no uncertain tax positions that would require financial statement recognition, de-recognition, or disclosure. Each of the Portfolio's federal tax returns filed in the 3-year period ended October 31, 2007 remains subject to examination by the Internal Revenue Service.

E Expense Reduction — State Street Bank and Trust Company (SSBT) serves as custodian of the Portfolio. Pursuant to the custodian agreement, SSBT receives a fee reduced by credits, which are determined based on the average daily cash balance the Portfolio maintains with

Tax-Managed Mid-Cap Core Portfolio as of April 30, 2008

NOTES TO FINANCIAL STATEMENTS (Unaudited) CONT'D

SSBT. All credit balances, if any, used to reduce the Portfolio's custodian fees are reported as a reduction of expenses in the Statement of Operations.

F Use of Estimates — The preparation of the financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of income and expense during the reporting period. Actual results could differ from those estimates.

G Indemnifications — Under the Portfolio's organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the Portfolio. Interestholders in the Portfolio are jointly and severally liable for the liabilities and obligations of the Portfolio in the event that the Portfolio fails to satisfy such liabilities and obligations; provided, however, that, to the extent assets are available in the Portfolio, the Portfolio may, under certain circumstances, indemnify interestholders from and against any claim or liability to which such holder may become subject by reason of being or having been an interestholder in the Portfolio. Additionally, in the normal course of business, the Portfolio enters into agreements with service providers that may contain indemnification clauses. The Portfolio's maximum exposure under these arrangements is unknown as this would involve future claims that may be made against the Portfolio that have not yet occurred.

H Interim Financial Statements — The interim financial statements relating to April 30, 2008 and for the six months then ended have not been audited by an independent registered public accounting firm, but in the opinion of the Portfolio's management, reflect all adjustments, consisting only of normal recurring adjustments, necessary for the fair presentation of the financial statements.

2 Investment Adviser Fee and Other Transactions with Affiliates

The investment adviser fee is earned by Boston Management and Research (BMR), a subsidiary of Eaton Vance Management (EVM), as compensation for management and investment advisory services rendered to the Portfolio. The fee is computed at an annual rate of 0.80% of the Portfolio's average daily net assets up to $500 million and at reduced rates as daily net assets exceed that level, and is payable monthly. Pursuant to a sub-advisory agreement, BMR pays Atlanta Capital Management Company, LLC (Atlanta Capital), an affiliate of EVM, a portion of its advisory fee for sub-advisory services provided to the Portfolio. For the six months ended April 30, 2008, the adviser fee was 0.80% (annualized) of the Portfolio's average daily net assets and amounted to $391,280. BMR has also agreed to reduce the investment adviser fee by an amount equal to that portion of commissions paid to broker dealers in execution of security transactions attributed to the Portfolio that is consideration for third-party research services. For the six months ended April 30, 2008, BMR waived $3,229 of its adviser fee. Atlanta Capital, in turn, waived $3,229 of its sub-adviser fee.

Except for Trustees of the Portfolio who are not members of EVM's or BMR's organizations, officers and Trustees receive remuneration for their services to the Portfolio out of the investment adviser fee. Trustees of the Portfolio who are not affiliated with the investment adviser may elect to defer receipt of all or a percentage of their annual fees in accordance with the terms of the Trustees Deferred Compensation Plan. For the six months ended April 30, 2008, no significant amounts have been deferred. Certain officers and Trustees of the Portfolio are officers of the above organizations.

3 Purchases and Sales of Investments

Purchases and sales of investments, other than short-term obligations, aggregated $18,789,771 and $24,466,635, respectively, for the six months ended April 30, 2008.

4 Federal Income Tax Basis of Investments

The cost and unrealized appreciation (depreciation) of investments of the Portfolio at April 30, 2008, as determined on a federal income tax basis, were as follows:

Aggregate cost	$	75,912,199
Gross unrealized appreciation	$	23,263,793
Gross unrealized depreciation		(1,400,718	)
Net unrealized appreciation	$	21,863,075

5 Line of Credit

The Portfolio participates with other portfolios and funds managed by EVM and its affiliates in a $200 million unsecured line of credit agreement with a group of banks. Borrowings are made by the Portfolio solely to facilitate the handling of unusual and/or unanticipated short-term cash requirements. Interest is charged to the Portfolio based on its borrowings at an amount above either the Eurodollar rate or Federal Funds rate. In addition, a fee computed at an annual rate of 0.07% on the daily unused portion of the

Tax-Managed Mid-Cap Core Portfolio as of April 30, 2008

NOTES TO FINANCIAL STATEMENTS (Unaudited) CONT'D

line of credit is allocated among the participating portfolios and funds at the end of each quarter. The Portfolio did not have any significant borrowings or allocated fees during the six months ended April 30, 2008.

6 Recently Issued Accounting Pronouncement

In September 2006, the FASB issued Statement of Financial Accounting Standards No. 157 (FAS 157), "Fair Value Measurements". FAS 157 defines fair value, establishes a framework for measuring fair value in accordance with generally accepted accounting principles and expands disclosure about fair value measurements. FAS 157 is effective for fiscal years beginning after November 15, 2007. As of April 30, 2008, management does not believe the adoption of FAS 157 will impact the amounts reported in the financial statements; however, additional disclosures may be required about the inputs used to develop the measurements of fair value and the effect of certain of the measurements on changes in net assets for the period.

Eaton Vance Tax-Managed Mid-Cap Core Fund

BOARD OF TRUSTEES' ANNUAL APPROVAL OF THE INVESTMENT ADVISORY AGREEMENT

Overview of the Contract Review Process

The Investment Company Act of 1940, as amended (the "1940 Act"), provides, in substance, that each investment advisory agreement between a fund and its investment adviser will continue in effect from year to year only if its continuance is approved at least annually by the fund's board of trustees, including by a vote of a majority of the trustees who are not "interested persons" of the fund ("Independent Trustees"), cast in person at a meeting called for the purpose of considering such approval.

At a meeting of the Boards of Trustees (each a "Board") of the Eaton Vance group of mutual funds (the "Eaton Vance Funds") held on April 21, 2008, the Board, including a majority of the Independent Trustees, voted to approve continuation of existing advisory and sub-advisory agreements for the Eaton Vance Funds for an additional one-year period. In voting its approval, the Board relied upon the affirmative recommendation of the Contract Review Committee of the Board (formerly the Special Committee), which is a committee comprised exclusively of Independent Trustees. Prior to making its recommendation, the Contract Review Committee reviewed information furnished for a series of meetings of the Contract Review Committee held in February, March and April 2008. Such information included, among other things, the following:

Information about Fees, Performance and Expenses

• An independent report comparing the advisory and related fees paid by each fund with fees paid by comparable funds;

• An independent report comparing each fund's total expense ratio and its components to comparable funds;

• An independent report comparing the investment performance of each fund to the investment performance of comparable funds over various time periods;

• Data regarding investment performance in comparison to relevant peer groups of funds and appropriate indices;

• Comparative information concerning fees charged by each adviser for managing other mutual funds and institutional accounts using investment strategies and techniques similar to those used in managing the fund;

• Profitability analyses for each adviser with respect to each fund;

Information about Portfolio Management

• Descriptions of the investment management services provided to each fund, including the investment strategies and processes employed, and any changes in portfolio management processes and personnel;

• Information concerning the allocation of brokerage and the benefits received by each adviser as a result of brokerage allocation, including information concerning the acquisition of research through "soft dollar" benefits received in connection with the funds' brokerage, and the implementation of a soft dollar reimbursement program established with respect to the funds;

• Data relating to portfolio turnover rates of each fund;

• The procedures and processes used to determine the fair value of fund assets and actions taken to monitor and test the effectiveness of such procedures and processes;

Information about each Adviser

• Reports detailing the financial results and condition of each adviser;

• Descriptions of the qualifications, education and experience of the individual investment professionals whose responsibilities include portfolio management and investment research for the funds, and information relating to their compensation and responsibilities with respect to managing other mutual funds and investment accounts;

• Copies of the Codes of Ethics of each adviser and its affiliates, together with information relating to compliance with and the administration of such codes;

• Copies of or descriptions of each adviser's proxy voting policies and procedures;

• Information concerning the resources devoted to compliance efforts undertaken by each adviser and its affiliates on behalf of the funds (including descriptions of various compliance programs) and their record of compliance with investment policies and restrictions, including policies with respect to market-timing, late trading and selective portfolio disclosure, and with policies on personal securities transactions;

• Descriptions of the business continuity and disaster recovery plans of each adviser and its affiliates;

Eaton Vance Tax-Managed Mid-Cap Core Fund

BOARD OF TRUSTEES' ANNUAL APPROVAL OF THE INVESTMENT ADVISORY AGREEMENT CONT'D

Other Relevant Information

• Information concerning the nature, cost and character of the administrative and other non-investment management services provided by Eaton Vance Management and its affiliates;

• Information concerning management of the relationship with the custodian, subcustodians and fund accountants by each adviser or the funds' administrator; and

• The terms of each advisory agreement.

In addition to the information identified above, the Contract Review Committee considered information provided from time to time by each adviser throughout the year at meetings of the Board and its committees. Over the course of the twelve-month period ended April 30, 2008, the Board met eleven times and the Contract Review Committee, the Audit Committee and the Governance Committee, each of which is a Committee comprised solely of Independent Trustees, met twelve, seven and five times, respectively. At such meetings, the Trustees received, among other things, presentations by the portfolio managers and other investment professionals of each adviser relating to the investment performance of each fund and the investment strategies used in pursuing the fund's investment objective. The Portfolio Management Committee and the Compliance Reports and Regulatory Matters Committee are newly established and did not meet during the twelve-month period ended April 30, 2008.

For funds that invest through one or more underlying portfolios, the Board considered similar information about the portfolio(s) when considering the approval of advisory agreements. In addition, in cases where the fund's investment adviser has engaged a sub-adviser, the Board considered similar information about the sub-adviser when considering the approval of any sub-advisory agreement.

The Contract Review Committee was assisted throughout the contract review process by Goodwin Procter LLP, legal counsel for the Independent Trustees. The members of the Contract Review Committee relied upon the advice of such counsel and their own business judgment in determining the material factors to be considered in evaluating each advisory and sub-advisory agreement and the weight to be given to each such factor. The conclusions reached with respect to each advisory and sub-advisory agreement were based on a comprehensive evaluation of all the information provided and not any single factor. Moreover, each member of the Contract Review Committee may have placed varying emphasis on particular factors in reaching conclusions with respect to each advisory and sub-advisory agreement.

Results of the Process

Based on its consideration of the foregoing, and such other information as it deemed relevant, including the factors and conclusions described below, the Contract Review Committee concluded that the continuance of the investment advisory agreement of the Tax-Managed Mid-Cap Core Portfolio (the "Portfolio"), the portfolio in which the Eaton Vance Tax-Managed Mid-Cap Core Fund (the "Fund") invests, with Boston Management and Research (the "Adviser"), and the sub-advisory agreement with Atlanta Capital Management Company, LLC (the "Sub-adviser"), including their fee structures, is in the interests of shareholders and, therefore, the Contract Review Committee recommended to the Board approval of the respective agreements. The Board accepted the recommendation of the Contract Review Committee as well as the factors considered and conclusions reached by the Contract Review Committee with respect to the agreements. Accordingly, the Board, including a majority of the Independent Trustees, voted to approve continuation of the investment advisory agreement and sub-advisory agreement for the Portfolio.

Nature, Extent and Quality of Services

In considering whether to approve the investment advisory agreement and sub-advisory agreements of the Portfolio, the Board evaluated the nature, extent and quality of services provided to the Portfolio by the Adviser and the Sub-adviser.

The Board considered the Adviser's and the Sub-adviser's management capabilities and investment process with respect to the types of investments held by the Portfolio, including the education, experience and number of its investment professionals and other personnel who provide portfolio management, investment research, and similar services to the Portfolio and whose responsibilities include supervising the Sub-adviser. The Board specifically noted the Adviser's in-house equity research capabilities. The Board also took into account the resources dedicated to portfolio management and other services, including the compensation paid to recruit and retain investment personnel, and the time and attention devoted to the Portfolio by senior management. With respect to the Sub-adviser, the Board took into account the resources available to the Sub-adviser in fulfilling its duties under the sub-advisory agreement and the Sub-adviser's experience in managing equity portfolios.

The Board also reviewed the compliance programs of the Adviser and relevant affiliates thereof, including the Sub-adviser. Among other matters, the Board considered compliance and reporting matters relating to personal trading by investment personnel, selective disclosure of portfolio holdings, late trading, frequent trading, portfolio valuation, business continuity and the allocation of investment

Eaton Vance Tax-Managed Mid-Cap Core Fund

BOARD OF TRUSTEES' ANNUAL APPROVAL OF THE INVESTMENT ADVISORY AGREEMENT CONT'D

opportunities. The Board also evaluated the responses of the Adviser and its affiliates to requests from regulatory authorities such as the Securities and Exchange Commission.

The Board also considered shareholder and other administrative services provided or managed by Eaton Vance Management and its affiliates, including transfer agency and accounting services. The Board evaluated the benefits to shareholders of investing in a fund that is a part of a large family of funds, including the ability, in many cases, to exchange an investment among different funds without incurring additional sales charges.

After consideration of the foregoing factors, among others, the Board concluded that the nature, extent and quality of services provided by the Adviser and Sub-adviser, taken as a whole, are appropriate and consistent with the terms of the investment advisory agreement and sub-advisory agreement, respectively.

Fund Performance

The Board compared the Fund's investment performance to a relevant universe of similarly managed funds identified by an independent data provider and appropriate benchmark indices. The Board reviewed comparative performance data for the one-, three- and five-year periods ended September 30, 2007 for the Fund. The Board noted that action was taken during 2006 and 2007 to improve the performance of the Fund and concluded that such actions were effective in improving the Fund's performance since that time.

Management Fees and Expenses

The Board reviewed contractual investment advisory fee rates, including any administrative fee rates, payable by the Portfolio and the Fund (referred to collectively as "management fees"). As part of its review, the Board considered the management fees (including administrative fees) and the Fund's total expense ratio for the year ended September 30, 2007, as compared to a group of similarly managed funds selected by an independent data provider. The Board considered the fact that the Administrator waived fees and/or paid expenses for the Fund and had agreed to waive fees and/or pay expenses in an additional amount for the next two years.

After reviewing the foregoing information, and in light of the nature, extent and quality of the services provided by the Adviser, the Board concluded that the management fees charged for advisory and related services and the Fund's total expense ratio are reasonable.

Profitability

The Board reviewed the level of profits realized by the Adviser and relevant affiliates thereof, including the Sub-adviser, in providing investment advisory and administrative services to the Portfolio, the Fund and to all Eaton Vance Funds as a group. The Board considered the level of profits realized without regard to revenue sharing or other payments by the Adviser and its affiliates to third parties in respect of distribution services. The Board also considered other direct or indirect benefits received by the Adviser and its affiliates in connection with its relationship with the Portfolio and the Fund, including the benefits of research services that may be available to the Adviser or Sub-adviser as a result of securities transactions effected for the Portfolio and other advisory clients.

The Board concluded that, in light of the foregoing factors and the nature, extent and quality of the services rendered, the profits realized by the Adviser and its affiliates, including the Sub-adviser, are reasonable.

Economies of Scale

In reviewing management fees and profitability, the Board also considered the extent to which the Adviser and its affiliates, on the one hand, and the Fund, on the other hand, can expect to realize benefits from economies of scale as the assets of the Fund and the Portfolio increase. The Board acknowledged the difficulty in accurately measuring the benefits resulting from the economies of scale with respect to the management of any specific fund or group of funds. The Board reviewed data summarizing the increases and decreases in the assets of the Fund and of all Eaton Vance Funds as a group over various time periods, and evaluated the extent to which the total expense ratio of the Fund and the profitability of the Adviser and its affiliates may have been affected by such increases or decreases. Based upon the foregoing, the Board concluded that the benefits from economies of scale are currently being shared equitably by the Adviser and its affiliates and the Fund. The Board also concluded that, assuming reasonably foreseeable increases in the assets of the Portfolio, the structure of the advisory fee, which includes breakpoints at several asset levels, can be expected to cause the Adviser and its affiliates and the Fund to continue to share such benefits equitably.

Eaton Vance Tax-Managed Mid-Cap Core Fund

OFFICERS AND TRUSTEES

Eaton Vance Tax-Managed Mid-Cap Core Fund

Officers Thomas E. Faust Jr. President and Trustee William H. Ahern, Jr. Vice President John R. Baur Vice President Michael A. Cirami Vice President Cynthia J. Clemson Vice President Charles B. Gaffney Vice President Christine M. Johnston Vice President Aamer Khan Vice President Thomas H. Luster Vice President Michael R. Mach Vice President Robert B. MacIntosh Vice President Duncan W. Richardson Vice President Judith A. Saryan Vice President Susan Schiff Vice President Thomas Seto Vice President David M. Stein Vice President Mark S. Venezia Vice President Adam A. Weigold Vice President Barbara E. Campbell Treasurer Maureen A. Gemma Secretary Paul M. O'Neil Chief Compliance Officer				Trustees Ralph F. Verni Chairman Benjamin C. Esty Allen R. Freedman William H. Park Ronald A. Pearlman Norton H. Reamer Heidi L. Steiger Lynn A. Stout

Eaton Vance Tax-Managed Mid-Cap Core Fund

OFFICERS AND TRUSTEES CONT'D

Tax-Managed Mid-Cap Core Portfolio

Officers Duncan W. Richardson President William O. Bell, IV Vice President Thomas E. Faust Jr. Vice President and Trustee William R. Hackney, III Vice President Marilyn Robinson Irvin Vice President Barbara E. Campbell Treasurer Maureen A. Gemma Secretary Paul M. O'Neil Chief Compliance Officer				Trustees Ralph F. Verni Chairman Benjamin C. Esty Allen R. Freedman William H. Park Ronald A. Pearlman Norton H. Reamer Heidi L. Steiger Lynn A. Stout

Investment Adviser of Tax-Managed Mid-Cap Core Portfolio
Boston Management and Research

The Eaton Vance Building
255 State Street
Boston, MA 02109

Sub-Adviser of Tax-Managed Mid-Cap Core Portfolio
Atlanta Capital Management Company, LLC

1349 West Peachtree Street
Suite 1600
Atlanta, GA 30309

Administrator of Eaton Vance Tax-Managed Mid-Cap Core Fund
Eaton Vance Management

The Eaton Vance Building
255 State Street
Boston, MA 02109

Principal Underwriter
Eaton Vance Distributors, Inc.

The Eaton Vance Building
255 State Street
Boston, MA 02109
(617) 482-8260

Custodian
State Street Bank and Trust Company

200 Clarendon Street
Boston, MA 02116

Transfer Agent
PFPC Inc.

Attn: Eaton Vance Funds
P.O. Box 9653
Providence, RI 02940-9653
(800) 262-1122

Eaton Vance Tax-Managed Mid-Cap Core Fund
The Eaton Vance Building
255 State Street
Boston, MA 02109

This report must be preceded or accompanied by a current prospectus. Before investing, investors should consider carefully the Fund's investment objective, risks, and charges and expenses. The Fund's current prospectus contains this and other information about the Fund and is available through your financial advisor. Please read the prospectus carefully before you invest or send money. For further information please call 1-800-225-6265.

1301-6/08 TMMCCSRC

Item 2. Code of Ethics

The registrant has adopted a code of ethics applicable to its Principal Executive Officer, Principal Financial Officer and Principal Accounting Officer. The registrant undertakes to provide a copy of such code of ethics to any person upon request, without charge, by calling 1-800-262-1122.

Item 3. Audit Committee Financial Expert

The registrant’s Board has designated William H. Park and Norton H. Reamer, each an independent trustee, as its audit committee financial experts. Mr. Park is a certified public accountant who is the Vice Chairman of Commercial Industrial Finance Corp (specialty finance company). Previously, he served as President and Chief Executive Officer of Prizm Capital Management, LLC (investment management firm) and as Executive Vice President and Chief Financial Officer of United Asset Management Corporation (“UAM”) (a holding company owning institutional investment management firms). Mr. Reamer is the President, Chief Executive Officer and a Director of Asset Management Finance Corp. (a specialty finance company serving the investment management industry) and is President of Unicorn Corporation (an investment and financial advisory services company). Formerly, Mr. Reamer was Chairman and Chief Operating Officer of Hellman, Jordan Management Co., Inc. (an investment management company) and Advisory Director of Berkshire Capital Corporation (an investment banking firm), Chairman of the Board of UAM and Chairman, President and Director of the UAM Funds (mutual funds).

Item 4. Principal Accountant Fees and Services

Not required in this filing

Item 5. Audit Committee of Listed registrants

Not required in this filing.

Item 6. Schedule of Investments

Please see schedule of investments contained in the Report to Stockholders included under Item 1 of this Form N-CSR.

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies

Not required in this filing.

Item 8. Portfolio Managers of Closed-End Management Investment Companies

Not required in this filing.

Item 9. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers.

Not required in this filing.

Item 10. Submission of Matters to a Vote of Security Holders.

No Material Changes.

Item 11. Controls and Procedures

(a) It is the conclusion of the registrant’s principal executive officer and principal financial officer that the effectiveness of the registrant’s current disclosure controls and procedures (such disclosure controls and procedures having been evaluated within 90 days of the date of this filing) provide reasonable assurance that the information required to be disclosed by the registrant has been recorded, processed, summarized and reported within the time period specified in the Commission’s rules and forms and that the information required to be disclosed by the registrant has been accumulated and communicated to the registrant’s principal executive officer and principal financial officer in order to allow timely decisions regarding required disclosure.

(b) There have been no changes in the registrant’s internal controls over financial reporting during the second fiscal quarter of the period covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 12. Exhibits

(a)(1)	Registrant’s Code of Ethics – Not applicable (please see Item 2).
(a)(2)(i)	Treasurer’s Section 302 certification.
(a)(2)(ii)	President’s Section 302 certification.
(b)	Combined Section 906 certification.

Signatures

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Tax-Managed Mid-Cap Core Portfolio

By:	/s/Duncan W. Richardson
	Duncan W. Richardson
	President


Date:	June 12, 2008

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.


By:	/s/Barbara E. Campbell
	Barbara E. Campbell
	Treasurer


Date:	June 12, 2008


By:	/s/Duncan W. Richardson
	Duncan W. Richardson
	President


Date:	June 12, 2008