Q4 Estimated Taxes: The January 15 Payment Explained
The holidays end, the decorations come down, and then comes a date many freelancers and small business owners forget: January 15. That is when the fourth-quarter estimated tax payment for 2026 is due. Miss it or underpay, and you may face a penalty on top of your tax bill. Here is how the payment works and how to get it right.
Key takeaways
- The fourth-quarter 2026 estimated tax payment (Form 1040-ES) is due January 15, 2027.
- It covers income earned in the last months of 2026 that had no tax withheld, such as self-employment or business profit.
- Safe harbor: paying 100% of last year's tax (110% if your prior-year AGI was over $150,000), or 90% of this year's tax, generally avoids the underpayment penalty.
- Work out the amount from your year-to-date profit, not a guess, and set the cash aside in December.
In the US, the tax system is pay as you go. Employees have tax withheld from every paycheck. If you are self-employed, a partner in a business, an S corporation owner with significant distributions, or someone with large side income, nobody withholds for you. Estimated tax payments are how you pay as you go instead.
The year is split into four payment periods, and the last one, for income earned at the end of the year, is due in mid-January. This article explains who needs to pay, how to calculate the amount and what happens if you get it wrong. It is general information, not tax advice. Rules and thresholds change, so check IRS.gov, your state tax agency or an accountant for your own situation.
Who needs to make the January 15 payment
You generally need to make estimated payments if you expect to owe tax for the year that is not covered by withholding and credits. Common examples include:
- Sole proprietors and freelancers whose business profit has no withholding.
- Single-member LLC owners taxed as sole proprietors.
- Partners and multi-member LLC members who pay tax on their share of profit.
- S corporation shareholders whose distributions and other income are not covered by salary withholding.
- Employees with side income, such as consulting, rentals or investment gains, large enough that withholding does not cover it.
If you made payments in April, June and September, January is simply the final installment. If you started your business late in 2026, it may be the first estimated payment you need to make, so do not assume you can wait until April.
What the Q4 payment actually covers
The fourth installment covers the last part of the year. For many seasonal businesses this is the busiest stretch: holiday sales, year-end projects and annual contracts often land in the final months. That means the Q4 payment can be larger than the earlier ones.
Estimated tax is not only income tax. If you are self-employed, it also needs to cover self-employment tax, which is how you pay Social Security and Medicare on your own earnings. Many first-year freelancers forget this part and underestimate what they owe.
Common mistake
Paying the same amount every quarter out of habit, even when the last months of the year were much stronger than the first. If your income jumped in October to December, a flat payment may leave you short and expose you to a penalty for that period. Recalculate before each payment, especially the last one.
How to work out the amount
There is no single right way, but the safest approach is a quick, honest calculation based on your actual numbers. Here is a simple method.
- Update your books through December. Record all income and expenses for the year, or at least through mid-December with a realistic estimate for the rest.
- Estimate full-year profit. Take income minus business expenses for 2026.
- Estimate your total tax. Use the worksheet in the Form 1040-ES instructions, your tax software or your accountant to estimate income tax and self-employment tax for the year.
- Subtract what is already paid. Deduct any withholding and the estimated payments you made earlier in the year.
- Check against safe harbor. Compare with the safe harbor amounts below and decide how much to pay on January 15.
Example
Imagine a freelance designer whose total 2025 tax was $12,000 and whose prior-year AGI was under $150,000. To meet the 100% safe harbor, she needs to pay at least $12,000 in total for 2026 through estimates and withholding, spread across the four due dates. She has paid $3,000 in each of the first three installments, so $3,000 on January 15 completes the safe harbor. If her 2026 tax turns out higher, she pays the rest by the April filing deadline, generally without an underpayment penalty. The numbers here are invented for illustration.
The safe harbor rules
The underpayment penalty is based on whether you paid enough tax, on time, during the year. The safe harbor rules give you a clear target. You generally avoid the penalty if your withholding and timely estimated payments add up to at least the smaller of:
| Option | What you need to pay during the year | Best when |
|---|---|---|
| Prior-year rule | 100% of last year's total tax | Your income is rising and last year's tax is known |
| Prior-year rule, higher income | 110% of last year's total tax, if prior-year AGI was over $150,000 | Higher earners with growing income |
| Current-year rule | 90% of this year's tax | Your income fell this year |
The prior-year rule is popular with growing businesses because it is predictable: you know last year's tax from your return, so you know the target from the start. The catch is that meeting the safe harbor only avoids the penalty. If you earned more this year, you still owe the rest of the tax by the April deadline, so keep setting money aside.
Pro tip
Open a separate savings account just for taxes and move a fixed share of every payment you receive into it. When January 15 arrives, the money is already there. Many owners find this one habit removes most of the stress of estimated taxes.
How to pay and what to keep
The IRS offers several ways to pay estimated tax, including online payment options on IRS.gov, your IRS online account and payment by check with a Form 1040-ES voucher. Check the current options on IRS.gov and pick one that gives you a clear confirmation.
- Pay early, not on the day. January 15 comes right after the holidays. Schedule the payment in the first week of January, or in late December if your cash allows.
- Save the confirmation. Keep the confirmation number or a copy of the check and voucher with your tax records.
- Record it in your books. Estimated tax for a sole proprietor is a personal tax payment, not a business expense. Record it as an owner draw or similar, not as an expense.
- Tell your accountant. Send a list of all four payments with dates and amounts when you hand over your year-end records.
Do not forget state estimated tax
Many states that have an income tax also expect estimated payments, often on similar dates but not always. Check your state tax agency's website for its own deadlines, forms and safe harbor rules, which can differ from the federal ones.
What if you cannot pay in full?
If January cash is tight, pay what you can by January 15. A partial payment reduces the penalty, because the penalty is calculated on the amount underpaid and how long it stays unpaid. Then pay the rest as soon as you are able.
If you expect a balance you cannot pay when you file in April, look at the payment plan options on IRS.gov early rather than ignoring the bill. Interest and penalties keep growing on unpaid tax, so delaying usually makes the problem bigger.
Why paying on time helps
- Avoids or reduces the underpayment penalty
- Spreads the tax cost instead of one big April bill
- Makes your cash flow easier to plan for the new year
What can go wrong
- January cash is often tight after holiday spending
- Overpaying ties up cash until you get a refund
- A guessed amount can still leave you short
Plan ahead for 2027
Once you have paid the January installment, use the moment to set up 2027 so it is easier. Take your 2026 tax from your return when it is ready and divide the safe harbor target across the four 2027 due dates. Put them in your calendar with reminders a week before each one. If you hire staff, start a new business line or expect a big change in income, ask your accountant to review your estimates mid-year rather than waiting until December.
Your January 15 checklist
- Bring your books up to date through December
- Estimate your 2026 profit, income tax and self-employment tax
- Total the withholding and estimated payments already made
- Compare with the 100% / 110% or 90% safe harbor targets
- Schedule the federal payment before January 15, 2027
- Check your state's estimated tax deadline and rules
- Save confirmations and record the payment correctly in your books
- Set 2027 due dates and reminders in your calendar
Frequently asked questions
What is the Q4 estimated tax payment?
It is the fourth and final installment of estimated tax for the 2026 tax year, paid with Form 1040-ES. It is due January 15, 2027, and covers income earned in the last part of 2026 without withholding.
What happens if I miss the January 15 payment?
You may owe an underpayment penalty, which works like interest on the amount you should have paid. Pay as soon as you can to limit it. Meeting a safe harbor through your other payments may mean no penalty applies.
Is it better to pay based on last year or this year?
If your income is growing, paying based on last year's tax (100%, or 110% if prior-year AGI was over $150,000) is predictable and generally avoids the penalty. If your income dropped, paying 90% of this year's tax may cost less. Your accountant can help you choose.
Is estimated tax a business expense?
No. For sole proprietors and pass-through owners, federal estimated tax is a personal income tax payment. Record it as an owner draw or similar so it does not reduce your business profit in the books.
Related reading
The bottom line
The January 15 payment is easy to overlook because it lands right after the holidays. Update your books, estimate your full-year tax, compare it with the safe harbor targets and schedule the payment early. Keep the confirmation, check your state's rules, and set up 2027 reminders while the process is fresh.
Estimated tax rules and penalties can change, and every situation is different. Check the current Form 1040-ES instructions on IRS.gov, or ask an accountant if your income changed a lot in 2026.
