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Level 1
June 22, 2026
Question

Underpayment penalty

  • June 22, 2026
  • 2 replies
  • 22 views

If I make extra 100K in capital gains this year but leave my tax witholding via paycheck to 110% of my last year’s tax, do I avoid underpayment penalty? I understand that at the time of tax filing I would be owing a lot of extra tax because of the extra income of 100K but I am simply trying to understand if I would be paying underpayment penalty or not. 

    2 replies

    baldietax
    Level 12
    June 22, 2026

    You got it - to avoid underpayment penalty you need to pay the smaller of - 90% of 2026 tax, or 100% of 2025 tax (110% if your 2025 AGI > 150k or 75k if filing MFS), either thru withholding or “timely” (usually quarterly) ES payments.  Withholding is always considered timely so if you didn’t make the adjustment yet it doesn’t matter if it’s unevenly withheld, but the later you do it the less paychecks you have to withhold from.  Then pay the balance of 2026 tax due when you file in April 2027.

     

    See instructions for Form 2210 for the official details.

    Level 15
    June 22, 2026

    “110% of last years tax” is generally line 24 of form 1040 times 110%.  But read the instructions for the detailed expalation on page 3

     

    https://www.irs.gov/pub/irs-pdf/i2210.pdf