5 U.S.C. § 5547

(a) An employee may be paid premium pay under sections 5542, 5545(a), (b), and (c), 5545a, 5545c, 5546(a) and (b), and 5550 only to the extent that the payment does not cause the aggregate of basic pay and such premium pay for any pay period for such employee to exceed the greater of— (1) the maximum rate of basic pay payable for GS–15 (including any applicable locality-based comparability payment under section 5304 or similar provision of law and any applicable special rate of pay under section 5305 or similar provision of law); or (2) the rate payable for level V of the Executive Schedule. (b) (1) Subject to regulations prescribed by the Office of Personnel Management, subsection (a) shall not apply to an employee who is paid premium pay by reason of work in connection with an emergency (including a wildfire emergency) that involves a direct threat to life or property, including work performed in the aftermath of such an emergency. (2) Notwithstanding paragraph (1), no employee referred to in such paragraph may be paid premium pay under the provisions of law cited in subsection (a) if, or to the extent that, the aggregate of the basic pay and premium pay under those provisions for such employee would, in any calendar year, exceed the greater of— (A) the maximum rate of basic pay payable for GS–15 in effect at the end of such calendar year (including any applicable locality-based comparability payment under section 5304 or similar provision of law and any applicable special rate of pay under section 5305 or similar provision of law); or (B) the rate payable for level V of the Executive Schedule in effect at the end of such calendar year. (3) Subject to regulations prescribed by the Office of Personnel Management, the head of an agency may determine that subsection (a) shall not apply to an employee who is paid premium pay to perform work that is critical to the mission of the agency. Such employees may be paid premium pay under the provisions of law cited in subsection (a) if, or to the extent that, the aggregate of the basic pay and premium pay under those provisions for such employee would not, in any calendar year, exceed the greater of— (A) the maximum rate of basic pay payable for GS–15 in effect at the end of such calendar year (including any applicable locality-based comparability payment under section 5304 or similar provision of law and any applicable special rate of pay under section 5305 or similar provision of law); or (B) the rate payable for level V of the Executive Schedule in effect at the end of such calendar year. (c) The Office of Personnel Management shall prescribe regulations governing the methods of applying subsection (b)(2) and (b)(3) to employees who receive premium pay under section 5545(c) or 5545a, or to firefighters covered by section 5545b who receive overtime pay for hours in their regular tour of duty, and the method of payment to such employees. Such regulations may limit the payment of such premium pay on a biweekly basis. (d) This section shall not apply to any employee of the Federal Aviation Administration or the Department of Defense who is paid premium pay under section 5546a. (e) Any supplemental pay resulting from receipt of the level 1 border patrol rate of pay or the level 2 border patrol rate of pay under section 5550 shall be considered premium pay in applying this section.