Cal. Pub. Util. Code § 969
In any ratemaking proceeding in which the commission authorizes a gas corporation to recover expenses for the gas corporation's transmission pipeline integrity management program established pursuant to Subpart O (commencing with Section 192.901) of Part 192 of Title 49 of the United States Code or related capital expenditures for the maintenance and repair of transmission pipelines, the commission shall require the gas corporation to establish and maintain a balancing account for the recovery of those expenses. Any unspent moneys in the balancing account in the form of an accumulated account balance at the end of each rate case cycle, plus interest, shall be returned to ratepayers through a true-up filing. Nothing in this section is intended to interfere with the commission's discretion to establish a two-way balancing account.
Ca. Pub. Util. Code § 969