Details of the regulatory assets and liabilities as of December 31, 2016 and 2015 are presented in the following table:

Regulatory Assets and Liabilities

	December 31,		December 31,
(millions)	2016		2015
Regulatory assets:
Regulatory tax asset ⁽¹⁾	$	85.6	$	74.6
Cost-recovery clauses - deferred balances ⁽²⁾		8.4		5.2
Cost-recovery clauses - offsets to derivative liabilities ⁽²⁾		0.0		26.2
Environmental remediation ⁽³⁾		36.9		54.0
Postretirement benefits ⁽⁴⁾		272.0		238.3
Deferred bond refinancing costs ⁽⁵⁾		5.7		6.5
Competitive rate adjustment ⁽²⁾		2.7		2.6
Other		9.4		10.7
Total regulatory assets		420.7		418.1
Less: Current portion		28.1		44.3
Long-term regulatory assets	$	392.6	$	373.8
Regulatory liabilities:
Regulatory tax liability	$	6.2	$	5.7
Cost-recovery clauses ⁽²⁾		111.8		54.2
Transmission and delivery storm reserve		56.1		56.1
Accumulated reserve—cost of removal ⁽⁶⁾		546.4		570.0
Other		24.3		0.7
Total regulatory liabilities		744.8		686.7
Less: Current portion		154.2		83.2
Long-term regulatory liabilities	$	590.6	$	603.5

(1)

The regulatory tax asset is primarily associated with the depreciation and recovery of AFUDC-equity. This asset does not earn a return but rather is included in capital structure, which is used in the calculation of the weighted cost of capital used to determine revenue requirements. It will be recovered over the expected life of the related assets.

(2)

These assets and liabilities are related to FPSC clauses and riders. They are recovered or refunded through cost-recovery mechanisms approved by the FPSC on a dollar-for-dollar basis in the next year. In the case of the regulatory asset related to derivative liabilities, recovery occurs in the year following the settlement of the derivative position.

(3)

This asset is related to costs associated with environmental remediation primarily at MGP sites. The balance is included in rate base, partially offsetting the related liability, and earns a rate of return as permitted by the FPSC. The timing of recovery is based on a settlement agreement approved by the FPSC.

(4)

This asset is related to the deferred costs of postretirement benefits and it is amortized over the remaining service life of plan participants. Deferred costs of postretirement benefits that are included in expense are recognized as cost of service for rate-making purposes as permitted by the FPSC.

(5)

This asset represents the past costs associated with refinancing debt. It does not earn a return but rather is included in capital structure, which is used in the calculation of the weighted cost of capital used to determine revenue requirements. It will be amortized over the term of the related debt instruments.

(6)

This item represents the non-ARO cost of removal in the accumulated reserve for depreciation. AROs are costs for legally required removal of property, plant and equipment. Non-ARO cost of removal represent estimated funds received from customers through depreciation rates to cover future non-legally required cost of removal of property, plant and equipment, net of salvage value upon retirement, which reduces rate base for ratemaking purposes. This liability is reduced as costs of removal are incurred.