5 CFR §550.1631

1. (a)An agent may not receive premium pay for night, Sunday, or holiday work for hours of regularly scheduled overtime work within the agent's regular tour of duty.
2. (b)An agent may receive premium pay for night, Sunday, or holiday work, as applicable, for hours not covered by paragraph (a) of this section, in accordance with 5 U.S.C. 5545(a) and (b) and section 5546 and corresponding regulations, except that section 5546(d) does not apply. (For an agent, pay for overtime work on a Sunday or holiday is determined under 5 U.S.C. 5542(g), not under section 5546(d).) The agent's rate of basic pay (without any overtime supplement) must be used in computing such premium payments.
3. (c)An agent may not be paid standby duty premium pay under 5 U.S.C. 5545(c)(1) or administratively uncontrollable overtime pay under 5 U.S.C. 5545(c)(2).