Cal. PUC § 751

(a) This section applies only to those public utilities over which the commission exercises its authority to fix rates and only to the extent the revenue requirements of the utility were based upon the tax rates in effect at the time rates were fixed for the utility by the commission. This section does not limit the discretionary authority of the commission to adjust any incentives provided pursuant to any state supervised or administered program, including the state’s telecommunications universal service programs administered pursuant to Chapter 1.5 (commencing with Section 270).

(b) The commission shall evaluate the full effect of the enactment of federal House Resolution 1 (Public Law 115-97) upon the expenses and tax liabilities incurred by public utilities for payment of federal taxes. If the commission determines that the projected expenses and tax liabilities for federal taxes that the commission has authorized in the rates for a public utility are materially affected by the enactment of federal House Resolution 1 (Public Law 115-97), the commission shall adjust the rates of the utility to reflect the changes in projected expenses and tax liabilities in light of the changes in federal law. This section does not limit the discretionary authority of the commission to determine the full effect of the changes in federal tax law on each utility’s cost of service, to utilize appropriate mechanisms at its disposal to track changes and adjust rates accordingly, and to allocate the impacts from changes in federal tax law over the period of time that results in the most reasonable allocation based on the particular circumstances of each utility.