There are lots of questions about Trump’s charitable giving—and many other deductions and declarations on his returns. Trump claimed millions of dollars in deductions for charitable giving—contributions that seem to have included both regular donations and deductions for conservation easements related to property he owned in New York state (that is, promises to not develop the land and preserve it as open space). In the report, the committee cited numerous aspects of Trump’s tax returns that should have been audited and repeatedly referred to his charitable donations and the lack of “substantiation” for them. The committee had a similar concern for other key portions of the returns involving deductions and the declaration of expenses: “There was little or no indication in the audit files that many of the numbers on the returns were flagged by the IRS for substantiation even when no supporting documents were provided for the return.” Or, put another way, the IRS simply took Trump’s word for it on most of the numbers he provided them.
"The returns also address one of the mysteries about Trump's last year in office: whether he gave away his presidential salary for all four years as he’d pledged to do. For 2020 at least, the answer appears to be no."
https://ca.news.yahoo.com/trumps-charitable-giving-dropped-to-0-by-the-time-he-left-office-returns-show-205022151.html