Each quarter he donates his salary to a pet cause, generally what he’s working on at the time.
Via Daily Caller:
White House press secretary Sarah Huckabee Sanders announced Tuesday that President Trump will donate his 2018 first quarter salary to the Department of Transportation to rebuild American infrastructure.
“To cure decades of neglect, we are committed to quickly building a safe, reliable and modern infrastructure to meet the needs of the American people and to fuel economic growth. And to help make this possible, we have a very special announcement today,” Sanders said.
“In keeping with his campaign pledge, the President donates his salary on a quarterly basis to further work being done on important projects. Most recently, the President donated his third quarter salary to help the Department of Health and Human Services combat the opioid epidemic.”