Cal. SHC § 8784

If there is a surplus remaining in the redemption fund after payment of all bonds and the interest thereon, that surplus shall first be applied to repayment to the city of any special taxes levied by it for the purpose of advancing funds under Part 13 (commencing with Section 8800) less its recovery on the sale or redemption of the properties assessed, and also of any costs incurred by it under this division. The remainder shall be repaid in accordance with the provisions of Section 8783 to persons paying supplemental assessments, if any, and the balance may be proportionately credited upon the final installments due upon the assessments securing the bonds and repaid to those persons whose assessments have been previously paid or may be transferred to the general fund of the city.