14 U.S.C. § 744 : US Code - Section 744: Appointment of a former Navy or Coast Guard officer

Search 14 U.S.C. § 744 : US Code - Section 744: Appointment of a former Navy or Coast Guard officer

A former officer of the Regular Navy or Coast Guard who applies
for a Reserve commission within one year of resigning the officer's
Regular commission, and who is appointed in the same grade
previously held in the Regular Navy or Coast Guard, shall be given
the same date or rank in that grade as that previously assigned to
the officer while a member of the Regular Navy or Coast Guard.