Annotation 5 - Article II
Clause 7 may be advantageously considered in the light of the rulings and learning arising out of parallel provision regarding judicial salaries. 100
Clause 7. The President shall, at stated Times, receive for his Services, a Compensation which shall neither be encreased nor diminished during the Period for which he shall have been elected, and he shall not receive within that Period any other Emolument from the United States, or any of them.
[Footnote 100] Cf. 13 Ops. Atty. Gen. 161 (1869), holding that a specific tax by the United States upon the salary of an officer, to be deducted from the amount which otherwise would by law be payable as such salary, is a diminution of the compensation to be paid to him which, in the case of the President, would be unconstitutional if the act of Congress levying the tax was passed during his official term.