5 U.S. Code § 3583
5.U.S. Code § 3583 is about Computations. It is under Part 3 (Employees) Subpart B (Employment and Retention) Subchapter 4 (Reemployment After Service With An International Organization) Chapter 35 (Part-time Career Employment Opportunities) of Title 5 (Government Organizations and Employees) of the Code.
A computation under this subchapter before reemployment is made in the same manner as if the employee had received basic pay, or basic pay plus additional pay in the case of a Congressional employee, at the rate at which it would have been payable had the employee continued in the position in which he was serving at the time of transfer.