Get your taxes done using TurboTax

to avoid penalty you need to have paid thru withholding and "timely" (usually quarterly) estimated taxes, the lesser of - 100% of your 2024 tax (110% if AGI > 150k as MFJ), or 90% of your 2025 tax.  You owe the remaining amount of tax when you file in April.

 

If your 2024 tax was $2220 and 2025 was much higher due to cap gains then presumably your safe harbor would be based on 100/110% of this prior year $2220 - but if you already paid that or more thru withholding you don't need to pay more thru estimated taxes.  If you are below that amount, to the extent you can increase withholding to meet it that will reduce the amount due from estimated taxes without penalty.

 

If you have to pay estimated tax to meet safe harbor but are doing so unevenly i.e you missed Q1/2 and just pay a one-off amount in Q3, then you will be assessed a penalty by default as IRS considers your income earned evenly and ES needs to be split evenly over the year (whereas withholding is always considered "timely" even if it comes later in the year).  You may be able reduce or eliminate this penalty by filing Form 2210 annualized income method; it depends your specific situation and the size of any penalty whether it's worthwhile as it's additional calculations for your AGI etc by quarter.

 

So I'd suggest

- check withholding before paying estimated tax and increase it if needed/possible

- remember to set aside whatever final tax you need to pay in April

- check Form 2210 for more details which has the safe harbor calculation on lines 1-9