Congress has the authority to obtain and reveal the confidential tax information of any taxpayer, including the president, without the taxpayer’s consent. Democrats have made many attempts to get Congress to use that authority to obtain President Trump’s tax returns. More than a million people have signed a White House petition asking for the same information.
 
So why hasn’t Congress acted?
Citation
George K. Yin, How a 1924 Law Could Unveil Trump Taxes, USA Today (March 30, 2017).