Just for comparison, I checked on when Obama finally released his birth certificate to quiet down the demands to see it. It was late April, 2011. Two and a half years after he was elected. And I don’t recall any Democrats demanding that he release it.
The natural citizenship of our President is a Constitutional requirement, so that birth certificate has a lot more importance than a tax form. Yet Democrats were perfectly fine with Obama not ever releasing that proof of citizenship.
Demands to see Trump’s tax returns are no more than more partisan politics. I hope he never releases his returns, just to see more Democrat heads explode.