When are 2026 quarterly estimated taxes due?

April 15, 2026; June 15, 2026; September 15, 2026; and January 15, 2027. You can skip the January payment if you file your 2026 return by February 1, 2027 and pay the full balance with it. A C corporation's fourth payment is due December 15 instead.

What is the safe harbor for estimated taxes?

You owe no underpayment penalty if your payments, made on time, add up to the smaller of 90% of your 2026 tax or 100% of your 2025 tax. If your 2025 adjusted gross income was over $150,000 ($75,000 if married filing separately), the prior-year figure is 110% instead of 100%. You generally only need to make estimated payments if you expect to owe at least $1,000.

What is the penalty for underpaying estimated taxes?

It works like interest. The IRS charges its underpayment rate, 7% a year for October through December 2026, compounded daily, on each quarter's shortfall from that quarter's due date until it is paid or the return is due. Being $4,500 short for a full year costs roughly $326 at that rate.

Do S-corp owners pay quarterly estimated taxes?

Usually, yes, personally. An S corporation does not pay federal income tax itself; the profit passes through to the owner's personal return. The owner's wages have tax withheld through payroll, and the owner pays estimates on Form 1040-ES to cover the tax on the rest of the profit. A C corporation pays its own estimates through EFTPS.

Should I book estimated tax payments as a business expense?

Not for a sole proprietorship, single-member LLC, partnership, or S corporation. Federal income tax on a pass-through's profit is the owner's personal tax, so a payment from the business account is an owner draw or distribution, not an expense. Booking it as an expense understates profit and puts a wrong number on the return.

Quarterly Estimated Taxes 2026: Due Dates and Safe Harbor

Quarterly estimated taxes for the 2026 tax year are due April 15, June 15, and September 15, 2026, and January 15, 2027. To avoid a penalty, pay the smaller of 90% of this year's tax or 100% of last year's (110% if last year's adjusted gross income was over $150,000), split across the four dates. That rule is called the safe harbor, and it means a business owner can know in April exactly what to pay all year, whatever the year brings. If you are short, the cost is interest at the IRS's underpayment rate, 7% a year for late 2026, on each quarter's shortfall.

Owners of profitable small businesses are the people this catches. No employer withholds tax from a business's profit, so the IRS expects you to pay it as you earn it.

Who has to pay estimates

You generally need to make estimated payments if you expect to owe at least $1,000 in federal tax for the year after withholding and credits. For a business owner, that is almost anyone with a profitable sole proprietorship, single-member LLC, partnership, or S corporation, because none of them withhold income tax from the profit itself.

The tax you are estimating is two taxes for most owners:

Income tax on the business profit, at your personal rates.
Self-employment tax if you are a sole proprietor or partner: 15.3% (12.4% Social Security and 2.9% Medicare) on 92.35% of net earnings, once net earnings reach $400. The Social Security part stops at the 2026 wage base of $184,500. An extra 0.9% Medicare tax applies above $200,000 for single filers.

On $100,000 of net profit, self-employment tax alone is $100,000 × 92.35% × 15.3% = $14,130, before any income tax.

The 2026 due dates

Payment	Due
First	April 15, 2026
Second	June 15, 2026
Third	September 15, 2026
Fourth	January 15, 2027

The dates are not evenly spaced: two months separate the first and second payments, and four separate the third and fourth. If you file your 2026 return by February 1, 2027 and pay everything you owe with it, you can skip the January payment.

The safe harbor, in plain numbers

You owe no underpayment penalty if your on-time payments add up to the smaller of:

90% of your 2026 tax, or
100% of your 2025 tax, or 110% if your 2025 adjusted gross income was over $150,000 ($75,000 if married filing separately).

The prior-year option is the one to use when the business is growing. Last year's tax is a number you already know, from a return already filed. Pay a quarter of it on each date and you are covered even if this year's profit doubles. You will owe the difference in April, but no penalty on it.

The current-year option is better when the year is worse than last year. If profit falls, 90% of this year's lower tax may be smaller than last year's whole bill.

A worked example

A sole proprietor's 2025 return showed $18,000 of total tax on adjusted gross income of $120,000. The books through September say 2026 is running ahead, and the full-year tax looks like $24,000.

Option	Calculation	Amount
90% of 2026 tax	$24,000 × 90%	$21,600
100% of 2025 tax	$18,000 × 100% (AGI under $150,000)	$18,000
Safe harbor (the smaller)		$18,000
Each of four payments	$18,000 ÷ 4	$4,500

Pay $4,500 on each date and there is no penalty, even though the year's real tax is $24,000. The remaining $6,000 is due when the return is filed in April 2027. That $6,000 is what the tax reserve is for, and how much to set aside covers it.

Had last year's AGI been $160,000, the prior-year figure would be $18,000 × 110% = $19,800, and each payment $4,950.

What being short actually costs

The underpayment penalty is not a flat fine. It works like interest: the IRS's underpayment rate, applied to each payment's shortfall from that payment's due date until it is paid. For October through December 2026, the rate is 7% a year, compounded daily, and the IRS sets it each quarter.

In the example above, skipping the April payment entirely and making it up with the return a year later costs roughly $4,500 × 7.25% (7% compounded daily for a year) = about $326, if the rate stays at 7%. Missing all four is a few hundred dollars more, not thousands.

That is worth knowing because it changes the decision. The penalty is real money, but it is not a reason to starve the business of cash in a slow month. A shop that needs the money for payroll in June is better off paying the June estimate in July than missing payroll. What is never worth it is ignoring estimates for a year and finding a five-figure bill in April with no cash set aside for it.

S-corp and C-corp owners

S corporations. The S-corp pays no federal income tax itself. Its profit passes through to the owner's personal return. The owner's salary has tax withheld through payroll, which counts toward the safe harbor. The owner pays estimates personally, on Form 1040-ES, for the tax on the profit above the salary. Pay them from your personal account, or take a distribution and pay from there.

C corporations. The company pays its own estimates through EFTPS, and its fourth payment is due December 15, not January 15.

Book the payment where it belongs

On a sole proprietorship, single-member LLC, partnership, or S corporation, a federal estimated tax payment made from the business account is not a business expense. It is the owner's personal income tax, so on the books it is an owner draw or a distribution.

Booking it as "Taxes" in expenses is one of the most common errors a CPA fixes in January. It understates the year's profit by the amount you paid, and if nobody catches it, it goes onto the return wrong. Payroll taxes, sales tax, and property tax are business expenses. Your federal income tax is not.

State estimates

Most states with an income tax have their own estimated payments, usually on similar dates. Texas has no personal income tax, so a Texas sole proprietor or S-corp owner pays federal estimates only. Check your state's revenue department for its dates and safe harbor.

How Poof tracks the estimates

Poof works out the four federal estimates from the safe-harbor rule: last year's tax, which you type in once, or this year's profit from the books, whichever is smaller. If your CPA gives you a number, the CPA's number wins. The four payments sit on the tax calendar on their real due dates, with who pays each one. Payments to the IRS and EFTPS are found in the bank feed and offered for the right quarter, you confirm each match, and a payment booked as an expense on a pass-through is flagged as an owner draw. Poof computes and reminds. It never pays the IRS, and it does not calculate state estimates.

*General information, not tax advice; your CPA has the final word.*

*Written by Austin Semple, a former controller: three years in audit, seven running the books for small businesses, and the founder of Poof. Poof keeps your four federal estimates on the tax calendar and finds the payments in your bank feed. Start a 30-day trial, no card required.*