In order to use our free online IRS Interest Calculator, simply enter how much tax it is that you owe (without the addition of your penalties as interest is not charged on any outstanding penalties), select the "Due Date" on which your taxes should have been paid (this is typically the 15 th of April), and lastly select the "Payment Date" (the date on which you expect to pay the full amount that you owe). Given that the IRS publishes their short-term interest rates at the end of each tax quarter, the latest date that you are able to select is the final day of the ongoing tax quarter.
IRS Interest CalculatorIf you don't pay your taxes on time, then the IRS will add interest to the amount that you already owe. More so, this interest is added on a daily occurrence, right up until you fully pay the money that you owe them. Even if you have requested a time extension, you must pay this interest as the extension only applies to the time that you have to pay the taxes.
Currently, the IRS interest rate which is applied to outstanding taxes is their short-term rate and an additional 3%. Every three months, the short-term rate is calculated by the IRS and is then published for taxpayers to see.
Something worth noting is that this free online IRS Interest Calculator is designed only for the use of individuals (both single and married) and not for the use of companies. Furthermore, the IRS interest rates which this calculator uses are updated at the end of each tax quarter.
Interest Amount = Amount Owed * Factor ,
Interest Amount = Amount Owed * ((1 + Daily Rate) days - 1) ,
Interest Amount = Amount Owed * (1 + Daily Rate) days - Amount Owed