I owe $9***n in tax this year. Again because of a stock sale/capital gains event. That is clearly over the $1000 lower limit that is suggested to generate an "underpayment penalty" Since I did not know/foresee in 2019 that I would be selling stock and owing capital gains in 2020, subsequently not paying estimated tax for 2020,
Will I be charged an underpayment penalty?
Is there any way to avoid an underpayment penalty?
Probably not, as you could have made an estimated tax payment when you actually sold the stock, or shortly thereafter. But some long term capital gains are taxes at 0% for Federal, depending upon your overall income. State taxes may be different, though.
Capital Gains Tax Rates: Here’s What You Need To Know for Tax Year 2020 (msn.com)
Generally, if you owe less than $1,000, you do not have to pay quarterly estimated tax payments and will not see an estimated tax penalty. If you pay at least 90% of your tax obligation or 100% of the tax owed in the prior year (whichever is smaller), then penalty can be avoided. If you are a high-income taxpayer, with an AGI over $150,000, then the 100% is increased to 110%.
For more information, see the following TurboTax article: