premium pay paid under the provisions of law cited in section 5547(a). (3) For purposes of applying this subsection to an employee under a premium pay limit established under an authority other than section 5547 of title 5, United States Code, the agency responsible for administering such limit shall determine what payments are considered premium pay. (e) Effective date This section shall take effect as if enacted on February 2, 2020. (f) Treatment of additional pay If application of this section results in the payment of additional premium pay to a covered employee of a type that is normally creditable as basic pay for retirement or any other purpose, that additional pay shall not— (1) be considered to be basic pay of the covered employee for any purpose