If you have a refund coming to you, there is no penalty for filing late. In fact, you may even get paid interest on the delayed refund! However, if you are filing late, the IRS will calculate penalties and interest based on the amount owed. Most late tax returns to take longer to process. Now, your failure to file penalty is going to be calculated based on the time from the deadline of your tax return to the date you actually filed your tax return. This penalty is 5% for each month the tax return is late, up to a total maximum penalty of 25%.