RATE AND REGULATORY MATTERS

Below is a summary of significant regulatory proceedings and related lawsuits. We are unable to predict the ultimate outcome of these matters, the timing of the final decisions of the various agencies and courts, or the impact on our results of operations, financial position, or liquidity.

Missouri

FAC Prudence Review

In April 2011, the MoPSC issued an order with respect to its review of Ameren Missouri's FAC for the period from March 1, 2009, to September 30, 2009. In this order, the MoPSC ruled that Ameren Missouri should have included in the FAC calculation all revenues and costs associated with certain long-term partial requirements sales that were made by Ameren Missouri because of the loss of Noranda's load caused by a severe ice storm in January 2009. As a result of the order, Ameren Missouri recorded a pretax charge to earnings of $18 million, including $1 million for interest, in 2011 for its obligation to refund to its electric customers the earnings associated with these sales previously recognized by Ameren Missouri during the period from March 1, 2009, to September 30, 2009. In May 2012, upon appeal by Ameren Missouri, the Cole County Circuit Court reversed the MoPSC's April 2011 order. In June 2012, the MoPSC and a group of large industrial customers filed an appeal of the Cole County Circuit Court's ruling to the Missouri Court of Appeals, Western District. In May 2013, the Missouri Court of Appeals upheld the MoPSC’s April 2011 order and reversed the Cole County Circuit Court’s May 2012 decision.

Ameren Missouri’s FAC calculation for the period from October 1, 2009, to May 31, 2011, excluded all revenues and costs associated with certain long-term partial requirements sales that were made by Ameren Missouri because of the loss of Noranda’s load caused by a severe ice storm in January 2009, similar to the FAC calculation for the period from March 1, 2009, to September 30, 2009. The MoPSC issued an order in July 2013, which was similar to the MoPSC's April 2011 order, as a result of which Ameren Missouri recorded a pretax charge to earnings of $26 million, including $1 million for interest, in 2013 for its estimated obligation to refund to Ameren Missouri’s electric customers the earnings associated with these sales previously recognized by Ameren Missouri for the period from October 1, 2009, to May 31, 2011. Ameren Missouri recorded the charge to “Operating Revenues – Electric” and the related interest to “Interest Charges” with a corresponding offset to “Current regulatory liabilities.” No similar revenues were excluded from FAC calculations after May 2011.

Separately, in July 2011, Ameren Missouri filed a request with the MoPSC for an accounting authority order that would allow Ameren Missouri to defer fixed costs totaling $36 million that were not previously recovered from Noranda as a result of the loss of load caused by the severe 2009 ice storm for potential recovery in a future electric rate case. In November 2013, the MoPSC issued an order approving Ameren Missouri's request for an accounting authority order. Ameren Missouri will seek to recover these fixed costs in its next electric rate case. In February 2014, MIEC filed an appeal of the accounting authority order to the Missouri Court of Appeals, Western District.

2012 Electric Rate Order

In December 2012, the MoPSC issued an order approving an increase for Ameren Missouri in annual revenues for electric service of $260 million. The revenue increase was based on a 9.8% return on equity, a capital structure composed of 52.3% common equity, and a rate base of $6.8 billion. Rate changes consistent with the order became effective on January 2, 2013. In January 2013, Ameren Missouri appealed the order with respect to the amount of property taxes included in the order to the Missouri Court of Appeals, Western District. Later in 2013, Ameren Missouri withdrew this appeal. In February 2013, the MoOPC, MIEC, and other parties filed separate appeals to the Missouri Court of Appeals, Western District, relating to the order's treatment of transmission costs in the FAC. In October 2013, the Missouri Court of Appeals, Western District, upheld the order. MoOPC, MIEC, and other parties filed a request to transfer their appeal to the Missouri Supreme Court, which was subsequently denied.

MEEIA Order

The MoPSC's December 2012 electric rate order approved Ameren Missouri's implementation of MEEIA megawatthour savings targets, energy efficiency programs, and associated cost recovery mechanisms and incentive awards. A MEEIA rider allows Ameren Missouri to collect from or refund to customers any annual difference in the actual amounts incurred and the projected amounts collected from customers for the MEEIA program costs and its projected lost revenues.

In addition to the program costs and lost revenues discussed above, the terms of Ameren Missouri's MoPSC-approved MEEIA programs offer an incentive award that would allow Ameren Missouri to earn additional revenues by achieving certain energy efficiency goals, including approximately $19 million if 100% of its energy efficiency goals are achieved during the three-year period, with the potential to earn more if Ameren Missouri's energy savings exceed those goals. Ameren Missouri must achieve at least 70% of its energy efficiency goals before it earns any incentive award. The recovery of an incentive award from customers, if the energy efficiency goals are achieved, is expected in 2017 through the above-mentioned rider.

Rate Design and Earnings Complaint Cases

On February 13, 2014, Ameren Missouri’s largest customer, Noranda, and 37 residential customers filed an earnings complaint case and a rate design complaint case with the MoPSC. In the earnings complaint case, Noranda and the residential customers asserted that Ameren Missouri’s electric delivery service business is earning more than the 9.8% return on equity authorized in the MoPSC's December 2012 electric rate order and requested the MoPSC to approve a reduction of the authorized return on equity to 9.4%. The rate design complaint case seeks to reduce Noranda’s electricity cost with an offsetting increase in electricity cost for Ameren Missouri’s other customers. The rate design complaint case asks the MoPSC to expedite its decision and grant relief by August 1, 2014.

The MoPSC has ordered Ameren Missouri to file a response to these two complaints by March 17, 2014. The MoPSC has no time requirement by which it must issue an order in these cases. Ameren Missouri opposes both requests filed by Noranda and the residential customers and will vigorously defend itself.

Illinois

IEIMA

Under the provisions of the IEIMA, Ameren Illinois' electric delivery service rates effective for customers' billings in 2013 were subject to an annual revenue requirement reconciliation to its actual 2013 costs. The 2013 revenue requirement reconciliation will be filed with the ICC in 2014. The approved annual revenue requirement reconciliation adjustment relating to 2013 will be reflected in customer rates beginning in January 2015. Throughout the year, Ameren Illinois records a regulatory asset or a regulatory liability and a corresponding increase or decrease to operating revenues for any differences between the revenue requirement in effect for that year and its estimate of the probable increase or decrease in the revenue requirement expected to ultimately be approved by the ICC based on that year's actual costs incurred. As of December 31, 2013, Ameren Illinois recorded a $65 million regulatory asset to reflect its expected 2013 revenue requirement reconciliation adjustment, which will be recovered from customers in 2015. Ameren Illinois also recorded a regulatory liability of $65 million and $55 million as of December 31, 2013, and December 31, 2012, respectively, to reflect its 2012 revenue requirement reconciliation adjustment, with interest, which will be refunded to customers in 2014.

In May 2013, Illinois enacted into law certain amendments to the IEIMA that modified its implementation. The law clarified that the IEIMA requires that the year-end rate base must be used to calculate the revenue requirement reconciliation and that the interest applied to the revenue requirement reconciliation and return on equity collar adjustments must be equal to a company's weighted-average return calculated under the formula rate.

In September 2012, the ICC issued an order in Ameren Illinois' initial filing under the IEIMA's performance-based formula rate framework, which Ameren Illinois appealed to the Appellate Court of the Fourth District of Illinois. In December 2012, the ICC issued an order in Ameren Illinois' update filing approving an Ameren Illinois electric delivery service revenue requirement of $765 million, based on 2011 recoverable costs and expected net plant additions in 2012. The delivery service rates became effective on January 1, 2013. In January 2013, Ameren Illinois filed an appeal of the ICC's update filing order to the Appellate Court of the Fourth District of Illinois. Both orders were consolidated for appeal with the primary issues being the treatment of accumulated deferred income taxes and vacation obligations as well as the calculation of Ameren Illinois' capital structure. In December 2013, the appellate court rendered its decision upholding the ICC's September and December 2012 orders. Ameren Illinois expects to file an appeal to the Illinois Supreme Court in March 2014.

In December 2013, the ICC issued an order in Ameren Illinois' annual update filing, which was based on 2012 recoverable costs and expected net plant additions for 2013, approving an Ameren Illinois electric delivery service revenue requirement of $788 million, before consideration of the 2012 revenue requirement reconciliation refund. The ICC order resulted in a net $45 million decrease in Ameren Illinois' electric delivery service revenue requirement. The calculation included a refund to customers of the 2012 revenue requirement reconciliation of $68 million, which included an estimate for interest through the end of 2014. However, this refund is partially offset by an annual revenue requirement increase of $23 million primarily due to higher recoverable costs in 2012 compared to 2011. The ICC order establishes rates for all of 2014. In January 2014, Ameren Illinois filed a request for rehearing with the ICC regarding the electric delivery service rate order, which the ICC denied. In February 2014, Ameren Illinois filed an appeal with the Appellate Court of the Fourth District of Illinois regarding the calculation of its capital structure and the treatment of accumulated deferred income taxes related to the transfer of former Ameren Missouri assets in Illinois to Ameren Illinois.

In the December 2013 order, the ICC disallowed, in part, the recovery from customers of the debt premium costs paid by Ameren Illinois for a tender offer in August 2012 to repurchase outstanding senior secured notes. At the time of the tender offer, Ameren Illinois recorded this loss on the reacquired debt as a regulatory asset. As a result of the ICC order, Ameren and Ameren Illinois each recorded in 2013 a pretax charge to earnings of $15 million relating to the partial disallowance of the premium costs. This charge was recorded in the statement of income for Ameren and Ameren Illinois as “Interest charges” with a corresponding decrease to “Regulatory assets.”

2013 Natural Gas Delivery Service Rate Order

In December 2013, the ICC issued a rate order that approved an increase in revenues for natural gas delivery service of $32 million. The revenue increase was based on a 9.1% return on equity, a capital structure composed of 51.7% common equity, and a rate base of $1.1 billion. The rate order was based on a 2014 future test year. The rate changes became effective January 1, 2014. In January 2014, Ameren Illinois filed a request for rehearing with the ICC regarding the natural gas delivery service rate order, which the ICC denied. Ameren Illinois expects to file an appeal of the ICC's order in March 2014.

Similar to the December 2013 electric rate order discussed above, this natural gas rate order included a partial disallowance relating to the August 2012 costs for the tender offer to repurchase outstanding senior secured notes. The pretax loss of $15 million discussed above includes the impact of both the December 2013 ICC electric and natural gas delivery service rate orders.

Natural Gas Consumer, Safety and Reliability Act

In July 2013, Illinois enacted the Natural Gas Consumer, Safety and Reliability Act, which encourages Illinois natural gas utilities to accelerate modernization of the state’s natural gas infrastructure and provides additional ICC oversight of natural gas utility performance. The law allows natural gas utilities the option to file for, and requires the ICC to approve, a rate rider mechanism to recover costs of certain natural gas infrastructure investments made between rate cases. The law does not require a minimum level of investment. Ameren Illinois expects to begin including investments under this regulatory framework in 2015. Ameren Illinois' decision to accelerate modernization of its natural gas infrastructure under this regulatory framework is dependent upon multiple considerations, including the allowed return on equity under this framework compared with other Ameren and Ameren Illinois investment options.

ATXI Transmission Project

ATXI's Illinois Rivers project is a MISO-approved project to build a 345-kilovolt line from western Indiana across the state of Illinois to eastern Missouri at an estimated cost of $1.1 billion. In August 2013, the ICC granted a certificate of public convenience and necessity and approved seven of a total of nine sections of the route and three of the proposed nine substations for the Illinois Rivers project. The ICC order indicated the project is necessary to address transmission and reliability needs in an efficient and equitable manner and that the project will benefit the development of a competitive electricity market. The order also indicated that ATXI is capable of constructing, managing and financing the project. In October 2013, the ICC granted ATXI's request for a rehearing to consider additional evidence regarding the two segments of the route and six substations that were not approved, as well as the requests for rehearing of certain other parties regarding two of the approved segments of the route. In February 2014, the ICC issued a final order on rehearing approving the remaining substations and routes for the Illinois Rivers project.

Federal

2011 Wholesale Distribution Rate Case

In January 2011, Ameren Illinois filed a request with FERC to increase its annual revenues for electric delivery service for its wholesale customers. These wholesale distribution revenues are treated as a deduction from Ameren Illinois' revenue requirement in retail rate filings with the ICC. In March 2011, FERC issued an order authorizing the proposed rates to take effect, subject to refund when the final rates are determined. Ameren Illinois reached an agreement with four of its nine wholesale customers. FERC has approved these settlement agreements, and any refund obligations related thereto have been made. The impasse with the remaining five wholesale customers has resulted in FERC litigation. In November 2012, a FERC administrative law judge issued an initial decision, which is now pending before FERC. The timing of a FERC decision is uncertain. In accordance with the administrative law judge's initial decision, Ameren and Ameren Illinois have both included on their balance sheets in "Current regulatory liabilities" an estimate of $13 million and $8 million as of December 31, 2013, and December 31, 2012, respectively, for the refund due to wholesale customers relating to billings for the period from March 2011 through December 2013.

Ameren Illinois Electric Transmission Rate Refund

In July 2012, FERC issued an order concluding that Ameren Illinois improperly included acquisition premiums, primarily goodwill, in determining the common equity used in its electric transmission formula rate, and thereby inappropriately recovered a higher amount from its electric transmission customers. The order required Ameren Illinois to make refunds to customers for such improperly included amounts. In August 2012, Ameren Illinois filed a request for a rehearing of this order. It is unknown when FERC will rule on Ameren's rehearing request, as it is under no deadline to do so.

Ameren Illinois submitted a refund report in November 2012 and concluded that no refund was warranted. Several wholesale customers filed a protest with FERC regarding Ameren's conclusion that no refund was warranted. In June 2013, FERC issued an order that rejected Ameren Illinois' November 2012 refund report and provided guidance as to the filing of a new refund report. In July 2013, Ameren Illinois filed a revised refund report based on the guidance provided in the June 2013 order, as well as a request for a rehearing of that order. Ameren Illinois' July 2013 refund report also concluded that no refund was warranted. Ameren Illinois estimated the maximum pretax charge to earnings for this possible refund obligation through December 31, 2013, would be $15 million, before interest charges. If Ameren Illinois were to determine that a refund to its electric transmission customers is probable, a charge to earnings would be recorded for the refund in the period in which that determination was made.

FERC Complaint Case

In November 2013, a customer group filed a complaint case with FERC seeking a reduction in the allowed return on common equity, as well as a limit on the common equity ratio, under the MISO tariff. Currently, the FERC-allowed return on common equity for MISO transmission owners is 12.38%. This complaint case could result in a reduction to Ameren Illinois' and ATXI's allowed return on common equity. That reduction could also result in a refund for transmission service revenues earned after the filing of the complaint case in November 2013. FERC has not issued an order in this case, and it is under no deadline to do so. Ameren is not able to predict when or how FERC will rule on this complaint case.

Ameren Missouri Power Purchase Agreement with Entergy

Beginning in 2005, FERC issued a series of orders addressing a complaint filed in 2001 by the Louisiana Public Service Commission (LPSC) against Entergy and certain of its affiliates. The complaint alleged unjust and unreasonable cost allocations. As a result of the FERC orders, Entergy began billing Ameren Missouri in 2007 for additional charges under a 165-megawatt power purchase agreement, which expired August 31, 2009. In May 2012, FERC issued an order stating that Entergy should not have included additional charges to Ameren Missouri under the power purchase agreement. Pursuant to the order, in June 2012, Entergy paid Ameren Missouri $31 million, with $24 million recorded as a reduction to “Purchased power” expense and $5 million for interest recorded as “Miscellaneous income” in the statement of income. The remaining $2 million was recorded as an offset to the FAC under-recovered regulatory asset for the amount refundable to customers. The amount of the Entergy refund recorded to the FAC regulatory asset related to the period when the FAC was effective; therefore, such costs were previously included in customer rates. In July 2012, Entergy filed an appeal of FERC's January 2010 and May 2012 orders to the United States Court of Appeals for the District of Columbia Circuit, which was subsequently dismissed on a procedural issue. In November 2013, Entergy refiled the appeal of FERC's May 2012 order with the United States Court of Appeals for the District of Columbia Circuit. Ameren is not able to predict when or how the court will rule on Entergy's appeal.

The LPSC appealed FERC’s orders regarding LPSC’s complaint against Entergy Services, Inc. to the United States Court of Appeals for the District of Columbia Circuit. In April 2008, that court ordered further FERC proceedings regarding LPSC’s complaint. The court ordered FERC to explain its previous denial of retroactive refunds and the implementation of prospective charges. FERC’s decision on remand of the retroactive impact of these issues could have a financial impact on Ameren Missouri. Ameren Missouri is unable to predict when or how FERC will respond to the court’s decisions. Ameren Missouri estimates that it could incur an additional expense of up to $25 million if FERC orders retroactive application for the years 2001 to 2005. Ameren Missouri believes that the likelihood of incurring any expense is not probable, and therefore no liability has been recorded as of December 31, 2013.

Combined Construction and Operating License

In 2008, Ameren Missouri filed an application with the NRC for a COL for a new nuclear unit at Ameren Missouri's existing Callaway County, Missouri, energy center site. In 2009, Ameren Missouri suspended its efforts to build a new nuclear unit at its existing Missouri nuclear energy center site, and the NRC suspended review of the COL application.

In March 2012, the DOE announced the availability of investment funds for the design, engineering, manufacturing, and sale of American-made small modular nuclear reactors. In April 2012, Ameren Missouri entered into an exclusive agreement to support Westinghouse's application for the first installment of DOE's small modular nuclear reactor investment funds. The DOE investment funding is intended to support engineering and design certifications and a COL for up to two small modular reactor designs over five years. A COL is issued by the NRC to permit construction and operation of a nuclear energy center at a specific site in accordance with established laws and regulations. Obtaining a COL from the NRC would not obligate Ameren Missouri to build a small modular reactor at the Callaway site; however, it would preserve the option to move forward in a timely fashion should conditions be right to build a small modular reactor in the future. A COL is valid for at least 40 years. In November 2012, the DOE awarded the first installment of investment funds for only one small modular reactor design, which was not the Westinghouse design. The DOE stated that a second installment of investment funds would be awarded during 2013. In December 2013, the DOE did not award Westinghouse the second installment of investment funds. Ameren Missouri's agreement to exclusively support Westinghouse's application expired in January 2014.

Ameren Missouri estimated the total cost that would be required to obtain the small modular reactor COL to be $80 million to $100 million. As of December 31, 2013, Ameren Missouri had capitalized investments of $69 million for the development of a new nuclear energy center. Ameren is currently evaluating all potential nuclear technologies in order to maintain an option for nuclear power in the future.

All of Ameren Missouri's capitalized investments for the development of a new nuclear energy center will remain capitalized while management pursues options to maximize the value of its investment. If efforts to license additional nuclear generation are abandoned or management concludes it is probable the costs incurred will be disallowed in rates, a charge to earnings would be recognized in the period in which that determination is made.

Pumped-storage Hydroelectric Energy Center Relicensing

In June 2008, Ameren Missouri filed a relicensing application with FERC to operate its Taum Sauk pumped-storage hydroelectric energy center for another 40 years. The existing FERC license expired on June 30, 2010. In July 2010, Ameren Missouri received a license extension that allows Taum Sauk to continue operations until FERC issues a new license. A FERC order is expected in 2014. Ameren Missouri cannot predict the ultimate outcome of FERC's review of the application.

Regulatory Assets and Liabilities

In accordance with authoritative accounting guidance regarding accounting for the effects of certain types of regulation, Ameren Missouri and Ameren Illinois defer certain costs as regulatory assets pursuant to actions of regulators or based on the expected ability to recover such costs in rates charged to customers. Ameren Missouri and Ameren Illinois also defer certain amounts as regulatory liabilities because of actions of regulators or because of the expectation that such amounts will be returned to customers in future rates. The following table presents Ameren’s, Ameren Missouri’s and Ameren Illinois’ regulatory assets and regulatory liabilities at December 31, 2013, and 2012:



	2013						2012
	Ameren Missouri		Ameren Illinois		Ameren			Ameren Missouri		Ameren Illinois		Ameren
Current regulatory assets:
Under-recovered FAC^(a)(b)	$	104	$	—	$	104		$	145	$	—	$	145
Under-recovered Illinois electric power costs^(c)	—		1		1			—		—		—
Under-recovered PGA^(c)	—		1		1			5		7		12
MTM derivative losses^(d)	14		36		50			13		77		90
Total current regulatory assets	$	118	$	38	$	156		$	163	$	84	$	247
Noncurrent regulatory assets:
Pension and postretirement benefit costs^(e)	$	44	$	140	$	184		$	348	$	424	$	772
Income taxes^(f)	230		7		237			231		4		235
Asset retirement obligations^(g)	—		5		5			—		5		5
Callaway costs^(a)(h)	40		—		40			44		—		44
Unamortized loss on reacquired debt^(a)(i)	77		74		151			81		100		181
Recoverable costs – contaminated facilities^(j)	—		271		271			—		248		248
MTM derivative losses^(d)	8		118		126			7		128		135
Storm costs^(k)	5		3		8			9		—		9
Demand-side costs before MEEIA implementation^(a)(l)	58		—		58			73		—		73
Reserve for workers’ compensation liabilities^(m)	6		6		12			6		6		12
Credit facilities fees⁽ⁿ⁾	5		—		5			6		—		6
Common stock issuance costs^(o)	4		—		4			7		—		7
Construction accounting for pollution control equipment^(a)(p)	22		—		22			23		—		23
Solar rebate program^(a)(q)	27		—		27			5		—		5
IEIMA revenue requirement reconciliation^(r)	—		65		65			—		—		—
Other^(s)(t)	8		12		25			12		19		31
Total noncurrent regulatory assets	$	534	$	701	$	1,240		$	852	$	934	$	1,786
Current regulatory liabilities:
Over-recovered FAC^(b)	$	26	$	—	$	26		$	—	$	—	$	—
Over-recovered Illinois electric power costs^(c)	—		51		51			—		58		58
Over-recovered PGA^(c)	5		29		34			—		15		15
MTM derivative gains^(d)	26		1		27			18		1		19
Wholesale distribution refund^(u)	—		13		13			—		8		8
IEIMA revenue requirement reconciliation^(r)	—		65		65			—		—		—
Total current regulatory liabilities	$	57	$	159	$	216		$	18	$	82	$	100
Noncurrent regulatory liabilities:
Income taxes^(v)	$	38	$	3	$	41		$	42	$	4	$	46
Removal costs^(w)	828		610		1,438			766		581		1,347
Asset retirement obligation^(g)	146		—		146			80		—		80
MTM derivative gains^(d)	1		—		1			2		—		2
Bad debt riders^(x)	—		8		8			—		12		12
Pension and postretirement benefit costs tracker^(y)	15		—		15			23		—		23
Energy efficiency riders^(z)	3		33		36			—		20		20
IEIMA revenue requirement reconciliation^(r)	—		—		—			—		55		55
FERC transmission revenue requirement reconciliation^(aa)	—		10		10			—		—		—
Other^(ab)	10		—		10			4		—		4
Total noncurrent regulatory liabilities	$	1,041	$	664	$	1,705		$	917	$	672	$	1,589


(a)	These assets earn a return.


(b)	Under-recovered or over-recovered fuel costs to be recovered through the FAC. Specific accumulation periods aggregate the under-recovered or over-recovered costs over four months, any related adjustments that occur over the following four months, and the recovery from customers that occurs over the next eight months.


(c)	Costs under- or over-recovered from utility customers. Amounts will be recovered from, or refunded to, customers within one year of the deferral.


(d)	Deferral of commodity-related derivative MTM losses or gains. See Note 7 – Derivative Financial Instruments for additional information.


(e)	These costs are being amortized in proportion to the recognition of prior service costs (credits), transition obligations (assets), and actuarial losses (gains) attributable to Ameren’s pension plan and postretirement benefit plans. See Note 11 – Retirement Benefits for additional information.


(f)	Offset to certain deferred tax liabilities for expected recovery of future income taxes when paid. This will be recovered over the expected life of the related assets.


(g)	Recoverable or refundable removal costs for AROs, including net realized and unrealized gains and losses related to the nuclear decommissioning trust fund investments. See Note 1 – Summary of Significant Accounting Policies – Asset Retirement Obligations.


(h)	Ameren Missouri’s Callaway energy center operations and maintenance expenses, property taxes, and carrying costs incurred between the plant in-service date and the date the plant was reflected in rates. These costs are being amortized over the remaining life of the energy center's current operating license, which expires in 2024.


(i)	Losses related to reacquired debt. These amounts are being amortized over the lives of the related new debt issuances or the original lives of the old debt issuances if no new debt was issued.


(j)	The recoverable portion of accrued environmental site liabilities that will be collected from electric and natural gas customers through ICC-approved cost recovery riders. The period of recovery will depend on the timing of remediation expenditures. See Note 15 – Commitments and Contingencies for additional information.

(k)

Actual storm costs in a test year that exceed the MoPSC staff’s normalized storm costs for rate purposes. As approved by the December 2012 MoPSC electric rate order, the 2006, 2007, and 2008 storm costs are being amortized through December 2014. As approved by the May 2010 MoPSC electric rate order, the 2009 storm costs are being amortized through June 2015. The Ameren Illinois total includes 2013 storm costs deferred in accordance with the IEIMA. These costs are being amortized over a five-year period beginning in 2013.

(l)

Demand-side costs incurred prior to implementation of the MEEIA in 2013, including the costs of developing, implementing and evaluating customer energy efficiency and demand response programs. Costs incurred from May 2008 through September 2008 are being amortized over a 10-year period that began in March 2009. Costs incurred from October 2008 through December 2009 are being amortized over a six-year period that began in July 2010. Costs incurred from January 2010 through February 2011 are being amortized over a six-year period that began in August 2011. Costs incurred from March 2011 through July 2012 are being amortized over a six-year period that began in January 2013.


(m)	Reserve for workers’ compensation claims. The period of recovery will depend on the timing of actual expenditures.


(n)	Ameren Missouri’s costs incurred to enter into and maintain the 2012 Ameren Missouri Credit Agreement. These costs are being amortized over five years, beginning in November 2012. These costs are being amortized to construction work in progress, which will be depreciated when assets are placed into service.


(o)	The MoPSC’s May 2010 electric rate order allowed Ameren Missouri to recover its portion of Ameren’s September 2009 common stock issuance costs. These costs are being amortized over five years, beginning in July 2010.


(p)	The MoPSC’s May 2010 electric rate order allowed Ameren Missouri to record an allowance for funds used during construction for pollution control equipment at its Sioux energy center until the cost of that equipment could be included in customer rates. These costs will be amortized over the expected life of the Sioux energy center, which is currently through 2033.


(q)	Costs associated with Ameren Missouri's solar rebate program beginning in August 2012 to fulfill Ameren Missouri's renewable energy portfolio requirement. The amortization period for these costs will be three years, commencing with the next Ameren Missouri electric rate case order.

(r)

The asset balance relates to the difference between Ameren Illinois' 2013 revenue requirement calculated under the IEIMA's performance-based formula ratemaking framework, and the revenue requirement included in customer rates for 2013. Subject to ICC approval, this asset will be collected from customers in 2015. The liability balance relates to the difference between Ameren Illinois' 2012 revenue requirement calculated under the IEIMA's performance-based formula ratemaking framework and the revenue requirement included in customer rates for 2012. This liability will be refunded to customers in 2014.

(s)

The Ameren Illinois total includes Ameren Illinois Merger integration and optimization costs, which are amortized over four years, beginning in January 2012. The Ameren Illinois total also includes costs related to the 2013 natural gas delivery service rate case costs, which are being amortized over a two-year period that began in January 2014. The Ameren Illinois total also includes a portion of the unamortized debt fair value adjustment recorded upon Ameren's acquisition of IP. This portion is being amortized over the remaining life of the related debt. At Ameren Missouri, the balance primarily includes the cost of renewable energy credits to fulfill its renewable energy portfolio requirement. Costs incurred from January 2010 through July 2012 are being amortized over three years, beginning in January 2013.


(t)	The Ameren total includes $5 million for ATXI's revenue requirement reconciliation adjustments for 2012 and 2013 calculated pursuant to the FERC's electric transmission formula ratemaking framework. These adjustments will be collected from customers in 2014 for the 2012 revenue requirement reconciliation and in 2015 for the 2013 revenue requirement reconciliation.


(u)	Estimated refund to wholesale electric customers. See 2011 Wholesale Distribution Rate Case above.


(v)	Unamortized portion of investment tax credits, federal excess deferred taxes, and uncertain tax position tracker. The tracker is being amortized over three years, beginning in January 2013. The unamortized portion of investment tax credit is being amortized over the expected life of the underlying assets.


(w)	Estimated funds collected for the eventual dismantling and removal of plant from service, net of salvage value, upon retirement related to our rate-regulated operations.

(x)

A regulatory tracking mechanism for the difference between the level of bad debt expense incurred by Ameren Illinois under GAAP and the level of such costs included in electric and natural gas rates. The over-recovery relating to 2011 was refunded to customers from June 2012 through May 2013. The over-recovery relating to 2012 is being refunded to customers from June 2013 through May 2014. The over-recovery relating to 2013 will be refunded to customers from June 2013 through May 2014.

(y)

A regulatory tracking mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri under GAAP and the level of such costs built into rates. For periods prior to August 2012, the MoPSC's December 2012 electric rate order directed the amortization to occur over five years, beginning in January 2013. For periods after August 2012, the amortization period will be determined in a future Ameren Missouri electric rate case.

(z)

The Ameren Illinois balance relates its regulatory tracking mechanism to recover its electric and natural gas costs associated with developing, implementing, and evaluating customer energy efficiency and demand response programs. This over-recovery will be refunded to customers over the following 12 months after the plan year. The Ameren Missouri balance relates to its MEEIA program costs incurred and projected lost revenues compared to the amount previously collected from customers. Beginning in January 2014, a MEEIA rider allows Ameren Missouri to collect from or refund to customers any annual difference in the actual amounts incurred and the projected amounts collected from customers for the MEEIA program costs and its projected lost revenues. Under the MEEIA rider, collections from or refunds to customers occur one year after the program costs and projected lost revenues are incurred.


(aa)	Ameren Illinois' 2013 revenue requirement reconciliation adjustment calculated pursuant to the FERC's electric transmission formula ratemaking framework. This liability will be refunded to customers in 2015.


(ab)	Balance primarily includes the costs of renewable energy credits to fulfill Ameren Missouri's renewable energy portfolio requirement from August 2012 through December 2013, which were less than the amount included in rates. The amortization period for this over-recovery will be determined in a future Ameren Missouri electric rate case.

Ameren Missouri and Ameren Illinois continually assess the recoverability of their regulatory assets. Under current accounting standards, regulatory assets are charged to earnings when it is no longer probable that such amounts will be recovered through future revenues. To the extent that payments of regulatory liabilities are no longer probable, the amounts are credited to earnings.