5 U.S.C. § 5522: Advance payments; rates; amounts recoverable

from a place outside the United States from which the Secretary of State determines it is in the national interest to require the departure of some or all employees, their dependents, or both; or from any place where there is imminent danger to the life of the employee or the lives of the dependents or immediate family of the employee. Subject to adjustment of the account of an employee under section 5524 of this title and other applicable statute, the advance payment of pay, allowances, and differentials is at rates currently authorized with respect to the employee on the date the advance payment is made under agency procedures governing advance payments under this subsection. The rates so authorized may not exceed the rates to which the employee was entitled immediately before issuance of the departure order. setoff against accrued pay, amount of retirement credit, or other amount due to the employee from the Government of the United States or the government of the District of Columbia; and such other method as is provided by law.