When I was figuring my underpayment penalty on TurboTax, I was asked which date I would pay the tax owed. I chose 03/08/21 thinking I would mail a check the next day, but I have decided to wait until my return is processed before paying. Is waiting increasing my penalty, or will my underpayment penalty be accurate as long as I pay before 04/15/21? I can't imagine it would fluctuate by more than a few dollars (my penalty was a small amount), so I am more interested in how this works than anything. When I reviewed my tax return, I could not find a reference to the date (03/08/21) that I had inputted or a number of days until payment or anything of that nature that was part of the underpayment calculation.
