E-file-9 - Calculating Penalty and Interest

If you think you owe penalty and/or interest but you do not want to calculate either or both yourself when you file your tax return, the Department of Revenue will do it for you and send you a bill.  If you file the return through TNTAP, your balance will update when your return processes.  Logging in the next day will allow you to see the balance after penalty and interest has been calculated and applied to the account.