Government Code §813.202

(a) Except as provided by Section 813.402 , any member may establish service credit in the retirement system for membership service not previously established. (b) A member may establish credit under this section by depositing with the retirement system in a lump sum a contribution computed as provided by Section 813.404 or 813.505 , plus interest computed on the basis of the state fiscal year at an annual rate of 10 percent from the date the service was performed to the date of deposit. (c) The state shall contribute for service established under this section an amount in the same ratio to the member's contribution and interest paid under Subsection (b) for the service as the state's contribution bears to the contribution for current service required of a member of the employee class at the time the service is established under this section. The state's contribution and interest must be paid from the fund or account from which the member receives compensation at the time the service is established or, if the member does not hold a position at the time the service is established, from the fund or account from which the member received compensation when the member most recently held a position.