What is an underpayment penalty?

An underpayment penalty is a fine charged by the IRS if you don't have enough tax withheld (or don't make estimated payments) throughout the year. You may also owe an underpayment penalty if you make your payments late in the year instead of paying as you go throughout the year.

We recommend filling out the underpayment penalty information to help you waive or reduce your penalty and avoid future correspondence and/or bills from the IRS.

Where do I enter an Underpayment Penalty (Form 2210)?