Cal. Health and Safety Code § 52517

Notwithstanding any other provisions of this part, only mortgage loans are eligible for buy-down under the provisions of this part which are presently, or are expected to be, insured in whole or part by the Federal Housing Administration or guaranteed in whole or part by the United States Veterans Administration, the Farmers Home Administration of the United States Department of Agriculture, an agency of the state, by a private insuring entity authorized to engage in such business, or by any combination of the above, in percentages determined by the agency by regulation adopted by the policy committee, except that such insurance or guarantee need not be required, in the discretion of the policy committee, if the amount of the mortgage loan is less than 80 percent of the appraised value of the property (under standards applicable to that lender) which is the security for the loan.