California Codes, Civil Code - CIV, Division 3 — Obligations, Part 3 — Obligations Imposed by Law, Section 1720

(a) If an obligee fails to give a timely response to an inquiry of an obligor concerning any debit or credit applicable to an obligation, he shall not be entitled to interest, financing charges, service charges, or any other similar charges thereon, from the date of mailing of the inquiry to the date of mailing of the response.

(b) For the purpose of subdivision (a):

(1) An “inquiry” is a writing which is posted by certified mail to the address of the obligee to which payments are normally tendered, unless another address is specifically indicated on the statement for such purpose, then to such address.

(2) A “response” is a writing which is responsive to an inquiry and mailed to the last known address of the obligor.

(3) A response is “timely” if it is mailed within 60 days from the date on which the inquiry was mailed.

(c) This section shall only apply to an obligation created pursuant to a retail installment account as defined by Section 1802.7.