@Carl wrote:
.....The IRS rules are, if what you owe at tax filing time is more than $1000 or more than 10% of your total tax liability, whichever is *HIGHER*, then an underpayment penalty will be assessed.
Those are not the IRS rules, which are correctly reproduced immediately below.
In general, taxpayers don’t have to pay a penalty if they meet any of these conditions:
- They owe less than $1,000 in tax with their tax return.
- Throughout the year, they paid the smaller of these two amounts:
- at least 90 percent (however, see 2018 Penalty Relief, below) of the tax for the current year
- 100 percent of the tax shown on their tax return for the prior year – this can increase to 110 percent based on adjusted gross income.
See https://www.irs.gov/newsroom/basics-of-estimated-taxes-for-individuals
