Q4 Estimated Taxes Are Due January 15: Who Needs to Pay and How Much
· RKube Services
The last 2025 estimated tax payment is due January 15, 2026. Here's who needs to pay, how the safe harbor rules work, and how to pay online.
Every January we get the same call. A freelancer or a small business owner had a strong fourth quarter, the holidays got busy, and they're suddenly wondering whether they were supposed to send the IRS something before tax season. If you earn income that doesn't have tax withheld from it, the answer is usually yes, and the deadline is next week.
The fourth and final estimated tax payment for 2025 is due Thursday, January 15, 2026.
Who Actually Needs to Pay
Estimated taxes exist because the U.S. tax system is pay-as-you-go. If you have a W-2 job, your employer handles that for you through withholding. If you don't, or if withholding doesn't cover everything, you're expected to pay in during the year.
In general, you should be making estimated payments if you expect to owe $1,000 or more for 2025 after subtracting withholding and credits. That usually includes:
- Self-employed people and single-member LLC owners whose income isn't subject to withholding, including self-employment tax.
- S corporation owners who take profits as distributions. Your salary runs through payroll with withholding, but the rest of the profit that flows to your K-1 doesn't.
- People with side income: consulting, rental property, a gig on the side, or significant investment gains on top of a regular paycheck.
Source: IRS: Estimated Taxes
Safe Harbor: The Rule That Protects You From Penalties
You don't have to predict your 2025 income perfectly. The IRS won't charge an underpayment penalty if your withholding plus timely estimated payments cover the smaller of:
- 90% of your 2025 tax, or
- 100% of your 2024 tax (the total tax on your 2024 return), rising to 110% if your 2024 adjusted gross income was more than $150,000 ($75,000 if married filing separately).
The prior-year option is the one most business owners lean on, because it's a known number. You look at last year's return and you're done guessing. You might still owe a balance in April, but you won't owe a penalty on top of it.
One detail people miss: the penalty is figured quarter by quarter. Paying everything in January doesn't fully erase a shortfall from April, June, or September. If your income came in unevenly, though (say most of it landed in the fall), the annualized income installment method on Form 2210 can reduce or eliminate the penalty for the earlier quarters.
Source: IRS Publication 505, Tax Withholding and Estimated Tax
Example Scenario
Take a self-employed consultant. Her 2024 return showed total tax of $14,000 and AGI of $120,000, so the 100% rule applies.
- Safe harbor target for 2025: $14,000, or $3,500 per quarter
- She paid $3,500 in April, June, and September: $10,500 so far
- 2025 turned out better than expected, and her actual tax will be around $20,000
If she pays the final $3,500 by January 15, she's hit 100% of last year's tax on schedule. She'll owe roughly $6,000 when she files in April, but no underpayment penalty.
If her 2024 AGI had been over $150,000, the target would have been 110% of $14,000, which is $15,400, or $3,850 a quarter.
A Tip for S Corporation Owners
If you're on your own payroll, keep this in mind for 2026. Federal income tax withheld from wages is generally treated as paid evenly throughout the year, no matter when it was actually withheld. So if you fall behind, increasing withholding on your last paychecks of the year can help cover earlier quarters in a way a late estimated payment can't. It's too late to use that for 2025, since December payroll has already run, but it's a useful lever to plan for this year.
How to Pay
The easiest options are online:
- IRS Direct Pay: free, pays straight from a checking or savings account, no enrollment needed. Choose "Estimated Tax" and tax year 2025. irs.gov/payments/direct-pay
- EFTPS: the Treasury's payment system. It requires enrollment, which takes some time, so it's better for next year than for next week. eftps.gov
- Your IRS Online Account: lets you pay and also see the payments you've already made. irs.gov/payments/your-online-account
Save the confirmation number. You'll want it when your return is prepared. Also keep in mind that most states with an income tax have their own estimated payment schedule, so check your state revenue department as well.
How RKube Helps
We work with owners on estimates during the year, not just at filing time. That includes:
- Calculating safe harbor amounts from your prior-year return
- Projecting current-year tax from up-to-date books when income is swinging
- Coordinating S corporation payroll withholding with estimated payments
- Tracking every payment so nothing gets missed on the return
If you'd like help getting 2026 estimates right from the start, you can start a free 30-day bookkeeping trial or call us at (984) 234-7030.
Final Thoughts
If you're self-employed, own an S corp, or have income without withholding, check where you stand before January 15. The safe harbor rules make this manageable: pick a target, pay it, and deal with the rest in April. Everyone's situation is different, so it's worth running the numbers with a tax professional if you aren't sure which rule applies to you.
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