Trump promised not to accept a paycheck, however... he had to modify his promise:

Trump's yearly salary is $400,000. Article II of the Constitution requires the president to be paid, 
    so Trump modified his promise to accept just $1 per year.

Here's where he's donated his salary... and also be aware that because he has not built up a CZARSHIP or a cadre of
 servants and assistants as his predecessor did, it's been reported he's also saved the taxpayers over $20 Million dollars in other costs.


First quarter, 2017: National Park Service (for battlefield maintenance)
Second quarter, 2017: Department of Education (for a camp for students focused on science, technology, engineering and math)
Third quarter, 2017: Department of Health and Human Services (for combating the opioid crisis)
Fourth quarter, 2017: Department of Transportation (for programs improving the nation’s infrastructure)
400K
First quarter, 2018: Department of Veterans Affairs (for caregiver programs)
Second quarter, 2018: Small Business Administration (for a veterans program)
Third quarter, 2018: National Institute on Alcohol Abuse and Alcoholism
Fourth quarter, 2018: Department of Homeland Security
800K
First quarter, 2019: Department of Agriculture
900K so far...