If you're a US freelancer or 1099 contractor, the last estimated-tax payment for 2026 is due Friday, January 15, 2027. Most of the stress around it comes from not knowing whether you're "caught up." You can answer that with three numbers.
Number 1: your safe-harbor target
You avoid the underpayment penalty if your 2026 payments (estimated payments plus any W-2 withholding) reach the smaller of:
- 100% of your total 2025 tax (110% if your 2025 AGI was over $150,000, or $75,000 if married filing separately), or
- 90% of your 2026 tax.
Option 1 is the one you can know today: it's the "total tax" line on last year's return. Divide it by four and that's what each quarter should have covered.
Number 2: what you've actually paid
Add up what you've sent the IRS for 2026 (Direct Pay, EFTPS or your IRS online account all show history) plus any federal withholding from a W-2 job. Withholding counts as paid evenly through the year, even if it all came out in December.
Number 3: the gap, quarter by quarter
The penalty is figured per installment, not on the yearly total. A big January payment closes the gap going forward, but it doesn't erase interest that already built up on an earlier short quarter.
Worked example, assuming 2025 total tax of $9,000 and AGI under $150,000:
| Due date | Required | Paid | Running shortfall |
|---|---|---|---|
| Apr 15, 2026 | $2,250 | $2,250 | $0 |
| Jun 15, 2026 | $2,250 | $0 | $2,250 |
| Sep 15, 2026 | $2,250 | $2,250 | $2,250 (the Sept payment covers June first) |
| Jan 15, 2027 | $2,250 | $4,500 | $0 |
You end the year at $9,000, so you hit safe harbor in total, but $2,250 was short from June 15 to September 15 and another $2,250 from September 15 to January 15. At an assumed 7% annual rate that's roughly $40 + $53, about $93. Annoying, not catastrophic, and it's why paying something now beats waiting.
The shortcut most people miss
If you file your 2026 return and pay everything you owe by February 1, 2027 (January 31 falls on a Sunday), you don't owe a penalty for skipping the January 15 payment. It doesn't fix earlier quarters, but it's a real option if your books are already in shape.
Quick checklist for the next few weeks
- Pull your 2025 total tax and compute the safe-harbor number.
- Total your 2026 payments and withholding.
- If you have a W-2 job too, extra withholding in December counts as if paid evenly all year, which can wipe out earlier shortfalls.
- Set aside 25 to 30% of each client payment until January 15 so the last payment isn't a surprise.
If you'd rather not do the arithmetic by hand, we built a free estimator that shows each step of the math: https://keelsheet.com/calculators/quarterly-estimated-tax/?utm_source=devto&utm_medium=community&utm_campaign=q4deadline&utm_content=jan15-article
Not tax advice. Rules from IRS Form 1040-ES, Form 2210 and Publication 505. Confirm your own numbers with IRS.gov or a tax professional.
