Protests have been taking place in more than 150 locations across the United States to call on President Donald Trump to release his tax returns.
Mr Trump broke a long-held tradition by not releasing his paperwork during his presidential campaign.
His critics want to know who he has been dealing with and if there are any conflicts of interest.
At least 21 people were arrested in Berkeley, California, in clashes between Trump opponents and supporters.
There is no law requiring presidents to release their tax returns, but Mr Trump has found himself under public pressure and some information from a 2005 tax return was leaked to the media last month.
The protests were timed to coincide with the traditional mid-April deadline for Americans to file their tax returns.
“I think it is critical we know about his investments, his donations and any entanglements he has,” said one protester, Chuck Wash, at a march in Washington DC.
The idea for the themed march came from law professor Jennifer Taub, who was angered when presidential adviser Kellyanne Conway said President Trump would not be releasing his tax returns because “people don’t care”.