I need to know what the penalty for underpayment of estimated tax was for 2024?

[Opus 17]

If you were assessed a penalty you would get a letter from the IRS.  If Turbotax calculated an estimated penalty, that will be on form 2210 in your tax return package from 2024.

The general formula has not changed, although it uses a variable interest rate.  The penalty is, roughly speaking, 1/2% per month of the amount owed, calculated from the date it was owed, plus about 1/2% per month interest on the entire amount owed, not just the penalty.  

[DawnC]

It depends.  For tax year 2024, the penalty for underpayment of estimated tax wasn’t a flat dollar amount — it was an interest-based charge calculated on underpaid amounts for each quarter of the year.    You may owe the penalty if either:

You didn’t pay at least 90% of your 2024 tax liability through withholding and estimated payments, or

You didn’t pay at least 100% of your 2023 tax (110% for high-income taxpayers) through withholding/estimated payments.

Two Ways to Pay Tax - IRS