37 U.S.C. § 1010 : US Code - Section 1010: Commissioned officers: promotion; effective date for pay and allowances

Search 37 U.S.C. § 1010 : US Code - Section 1010: Commissioned officers: promotion; effective date for pay and allowances

An officer of a uniformed service who is promoted to a grade
above second lieutenant or ensign is entitled to the pay and
allowances of the grade to which promoted on the effective date of
the promotion.