I just received a letter from IRS stating I have under paid my taxes. What I reported as my adjusted gross Income and my taxable Income are identical to the IRS calculation. So it appears that the only difference would be the tax rate which would appear to be a Quicken issue. As a result I am requireds to pay an additional $793.61 in taxes, penalties and interest. Please explain how this could have happened. When I went through inputing my tax information and did the check at the end there were no errors.