5 CFR 630.403: Substitution of sick leave for unpaid family and medical leave to care for a covered servicemember.

The amount of accumulated and accrued sick leave an employee may substitute for unpaid family and medical leave under 5 U.S.C. 6382(a)(3) for leave to care for a covered servicemember may not exceed a total of 26 administrative workweeks in a single 12-month period (or, for a part-time employee or an employee with an uncommon tour of duty, an amount of sick leave equal to 26 times the average number of hours in his or her scheduled tour of duty each week).