Opinion: Two surprising takes from Trump's tax returns | CNN

Surprise number two is that the IRS did nothing. At all. And this notwithstanding the fact that the Internal Revenue Manual, or IRM, contains a policy, in place since 1977, that the "[i]ndividual income tax returns for the President and Vice President are subject to mandatory examinations." But the IRS did not do any examination of Trump's tax returns until after the Democrats took control of the House, and Ways and Means Committee Chair Richard Neal sent a request on April 3, 2019…

https://www.cnn.com/2022/12/22/opinions/donald-trump-tax-returns-mccaffery/index.html

Many Republicans said congressional subpoenas were mandatory. Now they suggest they’re optional - The Washington Post

In the past few weeks, a growing number of Democratic lawmakers have called to begin impeachment proceedings against President Trump. This intensifying drumbeat stems in part from the Trump administration’s repeated defiance of congressional subpoenas...
https://www.washingtonpost.com/politics/2019/06/07/many-republicans-said-congressional-subpoenas-were-mandatory-now-they-suggest-theyre-optional/