Gov. Code, § 59284

Such proceeds and reinvestments in escrow or in trust shall be in an amount at the time of the issuance of such refunding bonds sufficient to meet the requirements of either subdivision (a) or (b) of this section. Such proceeds and reinvestments in escrow or in trust shall also be certified by a certified public accountant licensed to practice in this state to be of an amount sufficient to meet such requirements.

(a) Such proceeds and investments, together with any interest or other gain to be derived from any such investment, shall be in an amount at least sufficient to pay (i) the principal of, and interest and redemption premiums if any, on, the refunded bonds as they become due, or at designated dates prior to maturity if the legislative body has exercised or has obligated itself to exercise a redemption privilege on behalf of the local agency, and (ii) the designated costs of issuance of the refunding bonds; or

(b) Such proceeds and investments, together with any interest or other gain to be derived from any such investment, shall be in an amount at least sufficient to pay (i) the principal of, and interest and redemption premiums if any, on, the refunding bonds prior to the maturity of the bonds to be refunded or prior to a designated date or dates before the maturity of the bonds to be refunded if the legislative body has exercised or has obligated itself to exercise a redemption privilege on behalf of the local agency, (ii) the principal of, and any redemption premiums due on, such refunded bonds at maturity or at such designated date or dates and (iii) the designated costs of issuance of the refunding bonds.