Code of Federal Regulations Title 20. Employees' Benefits § 20.1002.267 How is compensation during the period of service calculated in order to determine the employee's pension benefits, if benefits are based on compensation?

(b)(1) Where the rate of pay the employee would have received is not reasonably certain, such as where compensation is based on commissions earned, the average rate of compensation during the 12–month period prior to the period of uniformed service must be used.

(2) Where the rate of pay the employee would have received is not reasonably certain and he or she was employed for less than 12 months prior to the period of uniformed service, the average rate of compensation must be derived from this shorter period of employment that preceded service.