Unlike employees, who have taxes withheld from every paycheck, most business owners must pay their income taxes in four installments throughout the year. These are quarterly estimated taxes, and missing them can trigger penalties and an unwelcome bill at filing time. This guide explains who has to pay, when payments are due, how to calculate them, and how to stay penalty-free in 2026.
Table of Contents
- What Quarterly Estimated Taxes Are
- Who Must Pay Them
- 2026 Due Dates and Payment Schedule
- How to Calculate Your Payments
- Safe Harbor Rules That Avoid Penalties
- Common Mistakes and How to Avoid Them
- Key Takeaways
What Quarterly Estimated Taxes Are
The U.S. tax system is pay-as-you-go: income is supposed to be taxed as it is earned. Employees satisfy this through withholding. Business owners — sole proprietors, partners, and S corporation shareholders — generally do not have withholding on business income, so they make estimated payments directly to the IRS four times a year using Form 1040-ES. These payments cover federal income tax plus self-employment tax (Social Security and Medicare) on net business earnings.
C corporations handle this differently, making estimated payments on Form 1120-W. But for the vast majority of small businesses — which are pass-through entities — the individual estimated tax system applies. State estimated taxes are usually required too, on a parallel schedule, so budget for both federal and state obligations.
Who Must Pay Them
You generally must make estimated payments if you expect to owe at least $1,000 in tax for the year after subtracting withholding and refundable credits. That threshold catches most profitable small businesses. If you are a sole proprietor netting roughly $15,000 or more in profit, you are very likely in estimated-tax territory once income and self-employment taxes are combined.
New businesses sometimes assume they can wait until the first tax return, but the IRS expects payments in the year income is earned. If your business is new and growing, you should start paying as soon as you project owing $1,000 or more. Farmers and fishermen follow a modified schedule with different rules, and retirees with business income on the side should not ignore the requirement either.
2026 Due Dates and Payment Schedule
Estimated payments are due four times a year, roughly 15 days after the end of each payment period. For calendar-year taxpayers in 2026, the federal due dates are:
| Payment | Income period covered | Due date |
|---|---|---|
| 1st quarter | January 1 – March 31 | April 15, 2026 |
| 2nd quarter | April 1 – May 31 | June 15, 2026 |
| 3rd quarter | June 1 – August 31 | September 15, 2026 |
| 4th quarter | September 1 – December 31 | January 15, 2027 |
If a due date falls on a weekend or holiday, it shifts to the next business day. Note the uneven periods: the IRS simply annualizes your income over these windows. You can pay online through IRS Direct Pay or the Electronic Federal Tax Payment System (EFTPS); see the IRS website for current payment options and Form 1040-ES worksheets.
How to Calculate Your Payments
The simplest approach is the prior-year method: take last year’s total tax, divide by four, and pay that each quarter. This works well if your income is stable. If your business is new or growing fast, project this year’s income instead: estimate your net profit, subtract deductions, apply the tax rates, add self-employment tax (roughly 15.3 percent on the first tier of earnings, with the Social Security portion phasing out above the annual wage base), and divide by four.
You do not have to pay in perfectly equal installments — you can adjust each quarter as your actual income becomes clear. Many owners recalculate after each quarter using year-to-date numbers, which prevents both overpaying (an interest-free loan to the government) and underpaying (penalties). Accounting software that tracks profit in real time makes this much easier, as our guide to reading a profit and loss statement explains. Business owners working from home should also review home office tax deductions before finalizing each quarter’s numbers, since missed write-offs inflate every payment.
Safe Harbor Rules That Avoid Penalties
The IRS charges an underpayment penalty if you pay too little during the year, but safe harbor rules let you avoid it entirely. You owe no penalty if your total withholding and timely estimated payments equal at least 90 percent of this year’s tax, or 100 percent of last year’s tax — 110 percent if your adjusted gross income exceeded $150,000 last year ($75,000 if married filing separately).
For most growing businesses, the prior-year safe harbor is the easiest shield: pay 100 (or 110) percent of last year’s tax in four installments and you cannot be penalized, even if this year’s income doubles. The one catch is cash flow — if last year was unusually profitable, you may overpay significantly. In that case, the annualized-income method on Form 2210 lets you match payments to when income was actually earned, which helps seasonal businesses especially.
Common Mistakes and How to Avoid Them
The most common error is simply forgetting the payments exist, especially in year one. Set calendar reminders and treat each due date like a bill. Second, many owners calculate only income tax and forget self-employment tax, which can add thousands to the bill. Third, owners sometimes skip the fourth-quarter payment because it is due in January — it still counts for the prior year.
Another frequent mistake is ignoring state estimated taxes, which carry their own penalties. And if your income is lumpy, do not just divide last year’s tax by four blindly — use the annualized method to keep early payments reasonable, a cash flow discipline that keeps money in your business longer.
