California Code, Civil Code - CIV § 8722

(a) The bond shall be executed by an admitted surety insurer that is either listed in the Department of the Treasury's Listing of Approved Sureties (Department Circular 570) or that has an A.M.  Best rating of A or better and has an underwriting limitation, under Section 12090 of the Insurance Code, greater than the amount of the bond.

(b) The bond shall be in an amount not less than 15 percent of the contract price for the work of improvement or, if the work of improvement is to be substantially completed within six months after the commencement of work, not less than 25 percent of the contract price.

(c) The bond shall be conditioned for payment on default by the owner of any undisputed amount pursuant to the contract that is due and payable for more than 30 days.