IRS underpayment rules

Generally, most taxpayers will avoid this penalty if they either owe less than $1,000 in tax after subtracting their withholding and refundable credits, or if they paid withholding and estimated tax of at least 90% of the tax for the current year or 100% of the tax shown on the return for the prior year, whichever is smaller—Read more at “Topic No. 306 Penalty for Underpayment of Estimated Tax.” 29 October 2019