Paying 100% of 2019 taxes exempts you from an underpayment PENALTY for 2020 taxes.
However, you still have to pay INTEREST on the underpayment amount. Since your cap gains were in Q-1 you’ll pay interest for most of the year.
Fortunately, current interest rates are historically low; so if you can make more money in the market it might pay to play it that way.
Good news is that you made a lot of money and you have some choices!
