Okla. Admin. Code § 260:40-24-6
Section 125 plans (also known as "salary reduction" or "cafeteria" plans) must meet a different set of rules. Under these plans, contributions (both from employer and/or employee) must meet "non-discrimination" rules. These rules require the employer to ensure that contributions do not favor higher compensated employees. The Plan Administrator shall reduce amounts of benefits payable to a participant to assure that the health savings account option is nondiscriminatory and in compliance with any provision of the Internal Revenue Code or other applicable law or regulation. Any such reduction of benefits shall be made by the Plan Administrator on a reasonable and nondiscriminatory basis. Enrollees may change their salary reduction amounts, prospectively, on a monthly basis. An ineligible participant will be allowed to revoke their election, prospectively.
Okla. Admin. Code § 260:40-24-6