California Code, Code of Civil Procedure - CCP § 704.960

(a) If a declared homestead is voluntarily sold, the proceeds of sale are exempt in the amount provided by Section 704.730 for a period of six months after the date of sale.

(b) If the proceeds of a declared homestead are invested in a new dwelling within six months after the date of a voluntary sale or within six months after proceeds of an execution sale or of insurance or other indemnification for damage or destruction are received, the new dwelling may be selected as a declared homestead by recording a homestead declaration within the applicable six-month period. In such case, the homestead declaration has the same effect as if it had been recorded at the time the prior homestead declaration was recorded.