Late Payment Penalty

The IRS charges you a late payment penalty along with interest if you owe tax after April 15 on individual returns. You can extend the time to file your return but not the time to pay the tax due. The late payment penalty is .5% of the unpaid balance for each month or part of a month up to a maximum of 25%. If you agree to an installment arrangement with the IRS, then the penalty is half the usual rate.