Okla. Admin. Code § 715:10-5-29
Sick leave can only be verified on termination of employment, or when filing a retirement contract. The verification must be made by the superintendent, financial officer, clerk of the board of education, or treasurer of the school district who must attest to the accuracy of the records used to make the verification. The verification must be based on records maintained and available at the local school and must be in keeping with local board policy. TRS will accept the employer's sick leave policy of awarding sick leave, however, in no instance will TRS accept more than fifteen (15) days of unused accumulated sick leave for any one (1) school year. An employer may not grant additional sick leave for the purpose of establishing, or adding to, the member's total service credit. Sick leave donated by other employees cannot be added to a member's sick leave record for purposes of this rule. The System may require the employing school to make available to it such other evidence as may be required to establish the member's eligibility for sick leave credit. Unused sick leave can be accumulated from the date of employment in the public schools of Oklahoma, or August 1, 1959, whichever occurred last, to the date of termination of employment in the public schools of Oklahoma. Reimbursements received by a member for unused sick leave accumulated prior to retirement shall not be considered as "regular annual compensation" as defined in OAC 715:10-13-1 and not subject to TRS contributions as provided for in Subchapter 13 of this chapter. (NOTE: Employers are encouraged to establish a system of tracking total days earned and used, even when the total days credited exceed the maximum limit set for local policy.)
Okla. Admin. Code § 715:10-5-29