I realized some gains from short and long-term capital assets sales. I didn't know that I need to estimate my tax on gains from my company stocks (RSUs and ESPP) sales. How do I know if I need to pay federal penalties for this and how do I calculate that on Turbotax?
See Estimated Tax Penalty Explained for details on the estimated tax penalty.
IRS Form 2210 (Underpayment of Estimated Tax by Individuals, Estates, and Trusts) calculates the underpayment penalty if you didn't withhold or pay enough taxes during the tax year.
Form 2210-F is a variation if you made at least 2/3 of your gross income from farming or fishing.
We'll automatically generate a Form 2210 if your return needs it. Or you can revisit this section:
Note: You'll need your prior year tax return to answer the questions.
(Optional) Keep going, and when you get to the Annualized Income Method screen, answer Yes if you want to see if we can reduce the penalty.