CONSOLIDATED INCOME TAX RETURNS.

(a) If an expense is allowed to be included in utility rates or an investment is included in the utility rate base, the related income tax benefit must be included in the computation of income tax expense to reduce the rates. If an expense is not allowed to be included in utility rates or an investment is not included in the utility rate base, the related income tax benefit may not be included in the computation of income tax expense to reduce the rates. The income tax expense shall be computed using the statutory income tax rates.

(b) The amount of income tax that a consolidated group of which an electric utility is a member saves, because the consolidated return eliminates the intercompany profit on purchases by the utility from an affiliate, shall be applied to reduce the cost of the property or service purchased from the affiliate.

(c) The investment tax credit allowed against federal income taxes, to the extent retained by the electric utility, shall be applied as a reduction in the rate-based contribution of the assets to which the credit applies, to the extent and at the rate allowed by the Internal Revenue Code.