aka Presidential Emoluments Clause

In Article II, Section 1, Clause 7, the President is prohibited from receiving “any other Emolument from the United States, or any of them” besides his fixed salary 

The term emolument in this context is broad and can include any profit, gain, or advantage — not just direct payments, but also benefits such as jobs, contracts, or other forms of compensation from federal or state governments 

Source: Congress.gov , Georgetown Law