What is the Connecticut Underpayment Penalty?
If you didn't make enough Connecticut estimated tax payments on time or have enough tax withheld during 2025, you may owe an underpayment penalty to Connecticut.
Usually, you don't need to calculate your own underpayment penalty. If you owe a penalty, the Connecticut Department of Revenue Services will figure the penalty for you and send you a bill after you have filed your tax return.
We recommend filling out the underpayment penalty information to help you waive or reduce your penalty and avoid future correspondence and/or bills from Connecticut.
Usually, you don't need to calculate your own underpayment penalty. If you owe a penalty, the Connecticut Department of Revenue Services will figure the penalty for you and send you a bill after you have filed your tax return.
We recommend filling out the underpayment penalty information to help you waive or reduce your penalty and avoid future correspondence and/or bills from Connecticut.
