California Code, Civil Code - CIV § 1917.031

(a) The term of the loan, excluding refinancing under Section 1917.033, shall be at least seven years, but not more than 30 years.

(b) The repayment schedule for the loan, excluding refinancing under Section 1917.033, shall be cast so that full amortization of the principal amount of the loan would occur in 30 years, regardless of the actual term of the loan. Any principal balance remaining at maturity shall be due and payable at that time, unless refinanced as provided in Section 1917.033. Monthly installment payments shall be equal in amount and in addition to amortization of principal, shall include fixed interest pursuant to subdivision (d).

(c) The loan shall be secured by a deed of trust or mortgage on the real property financed.

(d) The loan shall bear interest at a fixed rate, which shall be one-third below the prevailing rate in effect 90 days prior to the loan closing, or at another date between that date and the loan closing if mutually agreed by the lender and borrower.

(e) The borrower shall additionally be obligated to pay contingent deferred interest in the amount of one-third of the net appreciated value of the real property which secures the loan, at the time the property is sold (including a sale pursuant to a land sale contract), when title is transferred, other than a transfer specified in Section 2924.6, when a lease with an option to purchase is entered into, when a partnership is formed which in effect transfers the beneficial ownership to another person, when a trust is created which affects title to the property, upon a judicial or nonjudicial foreclosure sale, at the time the loan is prepaid in full, or upon the maturity of the loan, whichever first occurs.