5 U.S. Code § 5942a. Separate maintenance allowance for duty at Johnston Island
(a) Notwithstanding section 5536 of this title, and under regulations prescribed by the President, an employee of an Executive agency (other than a Government corporation) who is assigned to a post of duty at Johnston Island, a possession of the United States in the Pacific Ocean, is entitled to receive a separate maintenance allowance if the head of the employing agency finds that—
(1) it is necessary for the employee to maintain the employee’s spouse or dependents, or both, at a location other than Johnston Island—
The regulations prescribed by the President shall include provisions for determining the rate at which an allowance under this section shall be paid.
“The amendments made by subsection (a) [enacting this section] shall take effect on the first day of the first month beginning on or after the date of the enactment of this Act [Dec. 5, 1991].”