California Code, Civil Code - CIV § 2954.9

(b) Except as otherwise provided in Section 10242.6 of the Business and Professions Code, the principal and accrued interest on any loan secured by a mortgage or deed of trust on owner-occupied residential real property containing only four units or less may be prepaid in whole or in part at any time but only a prepayment made within five years of the date of execution of such mortgage or deed of trust may be subject to a prepayment charge and then solely as herein set forth. An amount not exceeding 20 percent of the original principal amount may be prepaid in any 12-month period without penalty. A prepayment charge may be imposed on any amount prepaid in any 12-month period in excess of 20 percent of the original principal amount of the loan which charge shall not exceed an amount equal to the payment of six months' advance interest on the amount prepaid in excess of 20 percent of the original principal amount.

(c) Notwithstanding subdivisions (a) and (b), there shall be no prepayment penalty charged to a borrower under a loan subject to this section if the residential structure securing the loan has been damaged to such an extent by a natural disaster for which a state of emergency is declared by the Governor, pursuant to Chapter 7 (commencing with Section 8550) of Division 1 of Title 2 of the Government Code, that the residential structure cannot be occupied and the prepayment is causally related thereto.