Cal. Sts. & High. Code § 18391

The city council may order by resolution that any part or amount of the next installment of the estimated cost and expense of any improvement be paid out of the city treasury from such fund as the city council may designate, in wihich case the liability and obligation to pay any sum so provided for shall accrue and become fixed upon the date of the levy of the installment assessment next succeeding the adoption of the resolution.