Yes, the minute he was sworn in, Trump was officially violating the Constitution through something called The Emoluments Clause. Norman Eisen, a fellow at the Brookings Institute, explains in a video for Think Progress,
The emoluments clause prohibits any person holding a federal office (such as, for example, the presidency) from accepting “any present, emolument, office, or title, of any kind whatever, from any king, prince, or foreign state.” In other words: People in the federal government aren’t allowed to take anything at all from any foreign government entity.
But Trump still retains ownership of his international business empire as president and is taking in a stream of payments from foreign governments — money that ultimately goes into his pockets.
Seth Meyers, who has been KILLING it on Late Night with A Closer Look, agrees and said Thursday night,
“The most exciting thing about tomorrow’s inauguration is this: the moment Trump takes his hand off that Bible tomorrow he may very well be in violation of the Constitution. That’s because he has not divested from his company or put his holdings in a blind trust….
I guess that explains the schedule, Noon swearing-in, 3 p.m. inaugural parade, 6 p.m. impeachment hearing.”