Cal. RTC § 4143

(a) Notwithstanding any other provision of law, in the case of a deficiency in the payment of taxes due and payable pursuant to this part, the tax collector, with the approval of the board of supervisors, may accept partial payments from the taxpayer. The partial payments shall be applied first to all penalties, interest, and costs, and the balance, if any, shall be applied to the taxes due. The difference between the amount paid by the taxpayer and the amount due shall be treated as a delinquent tax in the same manner as any other defaulted tax.

(b) Partial payments made pursuant to this section shall not be deemed a redemption, a partial redemption, or an installment payment under this part and they shall not alter either the date upon which the property became tax defaulted or the date the property becomes subject to a power of sale.

(c) These partial payments shall not be construed as altering the amount of defaulted taxes for purposes of publications.

(d) An election may be made by the taxpayer to pay the delinquent taxes in installments under Chapter 3 (commencing with Section 4186) and, if so, the installment payment shall be based upon the balance of the redemption amount determined pursuant to this section.

(e) When the taxpayer requests a partial payment, or when the tax collector receives such a payment, the tax collector shall inform the taxpayer of the provisions of subdivision (b) by return mail.

(f) (1) Upon authorization by ordinance by the board of supervisors, the tax collector may charge a fee to recover the reasonable costs of instituting and maintaining a partial payment arrangement under the provisions of this chapter. The fee is a charge described in paragraph (2) of subdivision (e) of Section 1 of Article XIII C of the California Constitution and shall be subject to the requirements of Chapter 12.5 (commencing with Section 54985) of Part 1 of Division 2 of Title 5 of the Government Code.

(2) The maximum fees that the tax collector may charge under the authorization of this section shall be established in the initial authorizing ordinance and limited to cost recovery only, pursuant to Section 54985 of the Government Code. Those fees, and any subsequent changes to those fees, shall be implemented consistent with Section 54985 of the Government Code, and after at least one public meeting, at which oral and written presentations may be made, as part of a regularly scheduled meeting held by the Board of Supervisors pursuant to Section 54986 of the Government Code.

(3) The ordinance authorizing the tax collector to charge a fee described in paragraph (1) shall require the fee to be paid prior to the application of any partial payments to penalties, interest, costs, and taxes due as specified in subdivision (a).