Q4 Estimated Tax Payment Calculator 2026
Your fourth 2026 estimated tax payment is due January 15, 2027. Enter your projected 2026 tax, your 2025 return and what you have paid so far to see the smallest Q4 payment that meets the safe harbor, and what will be left for April.
Your numbers
Enter the 2026 estimated payments you have already made, with dates. A 2025 refund applied to 2026 counts as a payment dated Apr 15, 2026.
Enter yearly amounts in US dollars. Results update as you type and never leave your browser.
Last reviewed: November 2, 2026.
How we calculate it
The fourth 2026 estimated tax payment is due January 15, 2027 (Form 1040-ES). This calculator works out the smallest Q4 payment that meets the safe harbor, using the same rules as Form 2210:
- $1,000 test. If your 2026 tax minus withholding is under $1,000, no estimated payments are required.
- Required annual payment = the lower of 90% of your 2026 tax or 100% of your 2025 tax (110% if your 2025 AGI was over $150,000, or $75,000 married filing separately). The 2025 option needs a 2025 return that covered 12 months and that you filed.
- Installments. 25% of that amount was due by each of April 15, June 15 and September 15, 2026, and January 15, 2027.
- Credits. Withholding is treated as paid in four equal parts on the due dates (IRC 6654(g)(1)). The Form 2210 instructions let you elect to use the actual dates your withholding was paid instead; this calculator assumes even spreading. Each payment counts on its date and goes first to the earliest installment still short.
- Q4 payment = everything still short after your payments, including earlier installments. Paying it by January 15 covers the fourth installment on time; earlier short parts become late payments, so a penalty runs on them from their due date to January 15.
- Penalty estimate on those late parts uses simple interest (amount × rate × days ÷ 365, IRC 6622(b)) at the IRS underpayment rates: 6% Apr–Jun and 7% Jul–Dec 2026. The rate for Jan 1–Apr 15, 2027 has not been announced; we assume 7% and you can change it. Penalty amounts are computed from exact amounts and rounded to the cent once per installment and rate period.
- February 1 option. If you file your 2026 return and pay all the tax by February 1, 2027, there is no penalty for the January 15 installment (IRC 6654(h)).
Not covered: the annualized income installment method (Schedule AI), farmers and fishermen, penalty waivers and state estimated taxes.
Worked example
Single filer. Projected 2026 tax $20,000 and $2,000 of W-2 withholding ($500 per due date). 2025 return: 12 months, filed, total tax $14,000, AGI $90,000. Paid $3,000 on Apr 15, Jun 15 and Sep 15, 2026.
| Step | Amount |
|---|---|
| Lower of 90% × $20,000 = $18,000 and 100% × $14,000 | $14,000 |
| Each installment (25%) | $3,500 |
| Apr, Jun, Sep: $500 withholding + $3,000 paid | covered on time |
| Jan 15, 2027: $3,500 − $500 withholding | $3,000 Q4 payment |
| Full balance: $20,000 − $2,000 − $9,000 | $9,000 |
| Left for Apr 15, 2027: $9,000 − $3,000 | $6,000, no penalty |
If the June payment was skipped (only Apr 15 and Sep 15 paid): the June installment gets just $500 on time; the September withholding and $2,500 of the September payment catch it up late, so September is left $3,000 short and gets $500 of January withholding. The Q4 payment is $6,000: $2,500 of September catch-up plus $3,500 for January. Estimated penalty: $3,000 late from Jun 15 to Sep 15 (15 days at 6% + 77 days at 7% = $51.70) plus $3,000 late from Sep 15 to Jan 15 (122 days at 7%, 15 of them at the assumed 2027 rate = $70.19): $121.89. The April balance is $6,000.
Related
- Safe harbor estimated tax calculator: what is left for every 2026 due date
- Estimated tax penalty calculator: the full Form 2210 penalty, day by day
- 1099 quarterly estimated tax calculator: project your 2026 tax
- Guide: the January 15, 2027 estimated tax payment
FAQ
When is the Q4 2026 estimated tax payment due?
January 15, 2027.
How much should my Q4 estimated payment be?
Enough to bring your withholding and estimated payments up to the safe harbor: the lower of 90% of your 2026 tax or 100% of your 2025 tax (110% if your 2025 AGI was over $150,000, or $75,000 married filing separately), with 25% counted by each due date.
Can I skip the January 15 payment?
Yes, if you file your 2026 return and pay all the tax by February 1, 2027 (January 31 is a Sunday). That removes the penalty for the fourth installment only.
Does a big Q4 payment fix missed earlier payments?
It stops the penalty on them from the day you pay, but the penalty for the time they were late still applies, because each installment is checked against its own due date.
Do I need a Q4 payment if I owe less than $1,000?
No. If your 2026 tax minus withholding is under $1,000, there is no underpayment penalty.
Can extra withholding in December replace the Q4 payment?
Often yes: withholding is treated as paid evenly on the four due dates, so W-2 withholding late in the year also covers earlier installments, unless you elect to use actual dates.
Sources
- IRS Form 1040-ES (2026): due dates and safe harbor
- IRS: Instructions for Form 2210 (regular method and Penalty Worksheet)
- IRS Tax Topic 306: Penalty for underpayment of estimated tax
- IRS Publication 505: Tax Withholding and Estimated Tax
- 26 U.S.C. § 6654 (estimated tax penalty)
- 26 U.S.C. § 6622(b) (no daily compounding for § 6654)
- IRS: Quarterly interest rates (2026: 7%, 6%, 7%, 7%)
Last reviewed November 2, 2026 by the Self Employed Math editorial team against the sources above.