How much interest does the IRS charge taxpayers who owe money? Many people wrongly believe that the IRS gouges taxpayers with sky-high interest rates. The actual interest rate is currently pretty low, only 3 percent. Interest rates are computed from the federal short-term rate and are adjusted quarterly. The current 3 percent rate will last through the third quarter of this year when it can be adjusted again. Do you owe money to the IRS? Call us, we can help.