Cal. Pub. Util. Code § 101255

After the conclusion of the hearing, and not later than August 1st of each year, and after making any revisions of the proposed budget which it may deem advisable either during or after the hearing, the board shall by resolution adopt the budget as finally determined by the board. Increases or additions shall not be made after the conclusion of the hearing, unless the items were proposed in writing and filed pursuant to Section 101253.