We had the following regulatory assets and liabilities as of December 31:


	2024			2023
	(in millions)
Regulatory assets
Winter Storm Uri (a)	$	109.5		$	199.6
Deferred energy and fuel cost adjustments (b)		62.8			55.1
Deferred gas cost adjustments (b)		14.5			4.1
Gas price derivatives (b)		2.9			5.1
Deferred taxes on AFUDC (b)		8.0			7.1
Employee benefit plans and related deferred taxes (c)		89.0			89.3
Environmental (b)		10.7			2.9
Loss on reacquired debt (b)		15.7			17.4
Deferred taxes on flow-through accounting (b)		87.7			74.7
Decommissioning costs (b)		2.4			2.4
Other regulatory assets (b)		24.5			22.4
Total regulatory assets		427.7			480.1
Less current regulatory assets		(154.8	)		(175.7	)
Regulatory assets, non-current	$	272.9		$	304.4

Regulatory liabilities
Deferred energy and gas costs (b)	$	91.9		$	88.9
Employee benefit plans and related deferred taxes (c)		36.7			36.2
Cost of removal (b)		197.0			181.9
Excess deferred income taxes (c)		238.5			247.1
Other regulatory liabilities (c)		4.6			12.5
Total regulatory liabilities		568.7			566.6
Less current regulatory liabilities		(94.1	)		(98.9	)
Regulatory liabilities, non-current	$	474.6		$	467.7

(a)

Timing of Winter Storm Uri incremental cost recovery and associated carrying costs vary by jurisdiction. See further information below.

(b)

Recovery/repayment of costs, but we are not allowed a rate of return.

(c)

In addition to recovery or repayment of costs, we are allowed a return on a portion of this amount or a reduction in rate base.

Regulatory assets represent items we expect to recover from customers through probable future rates.

Winter Storm Uri - Our Utilities received commission approval to recover incremental fuel, purchased power, and natural gas costs associated with Winter Storm Uri. In certain jurisdictions, we also received commission approval to recover carrying costs. As of December 31, 2024, we estimate that our remaining Winter Storm Uri regulatory asset has a weighted-average recovery period of 1.6 years.

Deferred Energy and Fuel Cost Adjustments - Deferred energy and fuel cost adjustments represent the cost of electricity delivered to our Electric Utilities’ customers that is either higher or lower than the current rates and will be recovered or refunded in future rates. Deferred energy and fuel cost adjustments are recorded and recovered or amortized as approved by the appropriate state regulatory commission. Our Electric Utilities file periodic quarterly, semi-annual, and/or annual filings to recover these costs based on the respective cost mechanisms approved by their applicable state regulatory commissions.

Deferred Gas Cost Adjustments - Our regulated Gas Utilities have GCA provisions that allow them to pass the cost of gas on to their customers. The GCA is based on forecasts of the upcoming gas costs and recovery or refund of prior under-recovered or over-recovered costs. To the extent that gas costs are under-recovered or over-recovered, they are recorded as a regulatory asset or liability, respectively. Our Gas Utilities file periodic monthly, quarterly, semi-annual, and/or annual filings to recover these costs based on the respective cost mechanisms approved by their applicable state regulatory commissions.

Gas Price Derivatives - Our regulated Gas Utilities, as allowed or required by state regulatory commissions, have entered into certain exchange-traded natural gas futures and options to reduce our customers’ underlying exposure to fluctuations in gas prices. Gas price derivatives represent our unrealized positions on our commodity contracts supporting our utilities. Gas price derivatives at December 31, 2024, are hedged over a maximum forward term of two years.

Deferred Taxes on AFUDC - The equity component of AFUDC is considered a temporary difference for tax purposes with the tax detriment being flowed through to customers as prescribed or allowed by regulators. If, based on a regulator’s action, it is probable the utility will recover the future increase in taxes payable represented by this flow-through treatment through a rate revenue increase, a regulatory asset is recognized. This regulatory asset is a temporary difference for which a deferred tax liability must be recognized. Accounting standards for income taxes specifically address AFUDC-equity and require a gross-up of such amounts to reflect the revenue requirement associated with a rate-regulated environment.

Employee Benefit Plans and Related Deferred Taxes - Employee benefit plans include the unrecognized prior service costs and net actuarial loss associated with our defined benefit pension plan and post-retirement benefit plans in regulatory assets rather than in AOCI. In addition, this regulatory asset includes the income tax effect of the adjustment required under accounting for compensation - defined benefit plans, to record the full pension and post-retirement benefit obligations. Such income tax effect has been grossed-up to account for the revenue requirement associated with a rate regulated environment.

Environmental - Environmental costs are associated with certain former manufactured gas plant sites. These costs are first offset by recognition of insurance proceeds and settlements with other third parties. Any remaining cost will be requested for recovery in future rate filings. Recovery for these specific environmental costs has not yet been approved by the applicable state regulatory commission and therefore, the recovery period is unknown at this time.

Loss on Reacquired Debt - Loss on reacquired debt is recovered over the remaining life of the original issue or, if refinanced, over the life of the new issue.

Deferred Taxes on Flow-Through Accounting - Under flow-through accounting, the income tax effects of certain tax items are reflected in our cost of service for the customer and result in lower utility rates in the year in which the tax benefits are realized. A regulatory asset was established to reflect that future increases in income taxes payable will be recovered from customers as the temporary differences reverse. As a result of this regulatory treatment, we continue to record a net tax benefit for costs considered currently deductible for tax purposes but are capitalized for book purposes.

Decommissioning Costs - South Dakota Electric and Colorado Electric received approval in 2014 for recovery of the remaining net book values and decommissioning costs of their decommissioned coal plants.

Regulatory liabilities represent items we expect to refund to customers through probable future decreases in rates.

Deferred Energy and Gas Costs - Deferred energy and gas costs that have been over-recovered through customer rates and will be returned to customers in future periods.

Employee Benefit Plans and Related Deferred Taxes - Employee benefit plans represent the cumulative excess of pension and retiree healthcare costs recovered in rates over pension expense recorded in accordance with ASC 715, Compensation-Retirement Benefits. In addition, this regulatory liability includes the income tax effect of the adjustment required under ASC 715, Compensation-Retirement Benefits, to record the full pension and post-retirement benefit obligations. Such income tax effect has been grossed-up to account for the revenue requirement associated with a rate regulated environment.

Cost of Removal - Cost of removal represents the estimated cumulative net provisions for future removal costs for which there is no legal obligation for removal included in depreciation expense.

Excess Deferred Income Taxes - The revaluation of the regulated utilities' deferred tax assets and liabilities due to the passage of the TCJA was recorded as excess deferred income taxes to be refunded to customers primarily using the normalization principles as prescribed in the TCJA. A majority of the excess deferred taxes are subject to the average rate assumption method, as prescribed by the IRS, and will generally be amortized as a reduction of customer rates over the remaining lives of the related assets.

On December 4, 2023, Arkansas Gas filed a rate review with the APSC seeking recovery of significant infrastructure investments in its 7,200-mile natural gas pipeline system. On October 1, 2024, Arkansas Gas received final approval for a settlement agreement for a general rate increase which is expected to generate $25.4 million of new annual revenue and shift $3.7 million of rider revenue to base rates. The approval allows a capital structure of 46% equity and 54% debt and a return on equity of 9.9%. New rates were effective October 14, 2024.

On June 14, 2024, Colorado Electric filed a rate review with the CPUC seeking recovery of significant infrastructure investments in its 3,200-mile electric distribution and 600-mile electric transmission systems. The rate review requested $36.7 million in new annual revenue with a capital structure of 53% equity and 47% debt and a return on equity of 10.5%. On November 22, 2024, Colorado Electric submitted rebuttal testimony, which updated its request to $25.1 million in new annual review with a capital structure of 53% equity and 47% debt and a return on equity of 9.8%. A final CPUC decision on the request is expected first quarter or early second quarter of 2025. Timing and implementation of new rates will be subject to a final decision.

On May 9, 2023, Colorado Gas filed a rate review with the CPUC seeking recovery of significant infrastructure investments in its 10,000-mile natural gas pipeline system. In March 2024, Colorado Gas received final approval for a settlement agreement for a general rate increase which is expected to generate $20.2 million of new annual revenue with a capital structure of 51% equity and 49% debt and a return on equity of 9.3%. Final rates were enacted on May 1, 2024, which replaced interim rates.

On May 1, 2024, Iowa Gas filed a rate review with the IUC seeking recovery of significant infrastructure investments in its 5,000-mile natural gas pipeline system. On December 2, 2024, Iowa Gas received final approval from the IUC for a settlement agreement for a general rate increase. The approved Black-box Settlement is expected to generate $15.0 million of new annual revenue based on a weighted average cost of capital of 7.2%. New rates were enacted on January 1, 2025, which replaced interim rates.

On February 3, 2025, Kansas Gas filed a rate review with the KCC seeking recovery of significant infrastructure investments in its 4,765-mile natural gas pipeline system. The rate review requests $17.2 million in new annual revenue with a capital structure of 50% equity and 50% debt and a return on equity of 10.5%. The request seeks to implement new rates in the second half of 2025.

On May 18, 2023, Wyoming Gas filed a rate review with the WPSC seeking recovery of significant infrastructure investments in its 6,400-mile natural gas pipeline system. On January 17, 2024, the WPSC approved a settlement agreement for a general rate increase which is expected to generate $13.9 million in new annual revenue with a capital structure of 51% equity and 49% debt and a return on equity of 9.85%. New rates were effective February 1, 2024. The agreement also included approval of a four-year extension of the Wyoming Integrity Rider.