14 U.S.C. § 273 : US Code - Section 273: Promotions; acceptance; oath of office

Search 14 U.S.C. § 273 : US Code - Section 273: Promotions; acceptance; oath of office

(a) An officer who receives an appointment under section 271 of
this title is considered to have accepted his appointment on its
effective date, unless he expressly declines the appointment.
(b) An officer who has served continuously since he subscribed to
the oath of office prescribed in section 3331 of title 5 is not
required to take a new oath upon his appointment in a higher grade.