what percentage of interest does the irs charge
1 If you owe tax and don't file on time, there is a penalty for not filing on time. 2  The failure to file penalty is usually five percent of the tax owed for each month, or part of a month that your return is late, up to five months.or more information about IRS notices and bills, refer to Publication 594 (PDF), The IRS Collection Process. For more information about penalty and interest charges, refer to Part One, Chapter 1, Filing Information, of Publication 17, Your Federal Income Tax for Individuals.