Gov. Code, § 17558

(a) The commission shall submit the adopted parameters and guidelines or a reasonable reimbursement methodology approved pursuant to Section 17557.2 to the Controller. As used in this chapter, a “reasonable reimbursement methodology” approved pursuant to Section 17557.2 includes all amendments to the reasonable reimbursement methodology. When the Legislature declares a legislatively determined mandate in accordance with Section 17573 in which claiming instructions are necessary, the Department of Finance shall notify the Controller.

(b) Not later than 90 days after receiving the adopted parameters and guidelines, a reasonable reimbursement methodology from the commission, or notification from the Department of Finance, the Controller shall issue claiming instructions for each mandate that requires state reimbursement, to assist local agencies and school districts in claiming costs to be reimbursed. In preparing claiming instructions, the Controller shall request assistance from the Department of Finance and may request the assistance of other state agencies. The claiming instructions shall be derived from the test claim decision and the adopted parameters and guidelines, reasonable reimbursement methodology, or statute declaring a legislatively determined mandate.

(c) The Controller shall, within 90 days after receiving amended parameters and guidelines, an amended reasonable reimbursement methodology from the commission or other information necessitating a revision of the claiming instructions, prepare and issue revised claiming instructions for mandates that require state reimbursement that have been established by commission action pursuant to Section 17557, Section 17557.2, or after any decision or order of the commission pursuant to Section 17559, or after any action by the Legislature pursuant to Section 17573. In preparing revised claiming instructions, the Controller may request the assistance of other state agencies.