The IRS is lowering to 80 percent the threshold required to qualify for estimated tax penalty relief for taxpayers whose 2018 federal income tax withholding and estimated tax payments fell short of their total tax liability for the year. Under the relief announced earlier this year, the threshold was 85 percent. Taxpayers who have not yet filed their 2018 tax return may request waiver of the estimated tax penalty by filing Form 2210, Underpayment of Estimated Tax by Individuals, Estates, and Trusts, with their tax return and following the directions in the just-released revision of the Instructions for Form 2210. To qualify for the waiver, they must have paid, through federal income tax withholding and estimated tax payments, at least 80 percent of their total tax liability for the 2018 tax year. Taxpayers who have already filed and paid the estimated tax penalty for tax year 2018 but who would have qualified for the waiver on Form 2210 may claim a refund of estimated tax penalties paid by filing Form 843, Claim for Refund and Request for Abatement, and including the statement "80% Waiver of estimated tax penalty" on line 7. They should leave lines 5a and 5b of the form blank. Form 843 can't be filed electronically. Notice 2019-25 PDF provides additional details related to this lower 80 percent threshold.