Here is the ACTUAL LAW stating that Trump must reveal his Tax Returns. IRS Code section 6103(f). Very Clear Meaning. It was Specifically designed to get Presidential Tax Returns during the Teapot Dome Scandal.

https://www.factcheck.org/2019/04/trump-wrong-about-tax-law/

US Code 6103(f) Disclosure to Committees of Congress
(1) Committee on Ways and Means, Committee on Finance, and Joint Committee on Taxation.
“Upon written request from the chairman of the Committee on Ways and Means of the House of Representatives, the chairman of the Committee on Finance of the Senate, or the chairman of the Joint Committee on Taxation, the Secretary shall furnish such committee with any return or return information specified in such request, except that any return or return information which can be associated with, or otherwise identify, directly or indirectly, a particular taxpayer shall be furnished to such committee only when sitting in closed executive session unless such taxpayer otherwise consents in writing to such disclosure.”

Or... in Laymans Terms: The Secretary of the IRS must provide ANYONE'S Tax Returns to a Closed Session of the Ways and Means Committee... 

https://www.law.cornell.edu/uscode/text/26/6103

Show US Trump's Tax Returns! It's the LAW... In Fact, "We the People" want to find out if Trump is a CROOK.

The American People Voted Against Trump in 2016. Hillary Clinton GOT MORE VOTES! So when Republicrimes say "We the People" voted to Let Trump Keep His Tax Returns SECRET, they are LYING. 

The law invoked last week by House Ways and Means Committee Chairman Richard Neal, D-Mass., empowers Congress to obtain the returns of any taxpayer directly from the Internal Revenue Service. 
https://www.npr.org/2019/04/09/711256462/white-house-lawyers-discussed-trump-tax-returns-with-treasury-department