Tax season is over, but if you had to pay an underpayment penalty, you may be able to get a refund for some of it. Because of the confusion about the Tax Cuts and Jobs Act, the IRS expanded the waiver for tax penalties for underpayment for this year only. In other years, you could avoid a penalty by withholding at least 90% of the tax due. This year, the IRS lowered that number to 85% and then again to 80% as the tax season wore on. I can help you file Form 843, Claim for Refund and Request for Abatement.