Quarterly estimated tax due dates for small businesses (tax years 2026 and 2027)

Many small business owners pay federal income tax in four installments across the year rather than one lump sum at filing. The IRS calls these estimated tax payments. This guide lists the federal due dates for tax years 2026 and 2027 and the forms used. Information only, not advice. State estimated taxes follow their own calendars and are out of scope here.

Who pays federal estimated tax

Estimated tax generally applies to income that is not subject to withholding. The IRS says individuals, including sole proprietors, partners and S corporation shareholders, generally have to make estimated tax payments if they expect to owe at least $1,000 in tax when their return is filed, after subtracting withholding and refundable credits. C corporations generally have to make estimated tax payments if they expect to owe $500 or more. For the exact tests and safe-harbor rules, see IRS: Estimated taxes and discuss your facts with a CPA or qualified accountant.

Forms used

• Form 1040-ES — individuals, including sole proprietors, single-member LLC owners, partners in a partnership and S corporation shareholders.
• Electronic deposit through EFTPS — the IRS directs calendar-year C corporations to deposit through the Electronic Federal Tax Payment System.
• Form 2210 — used by individuals, estates and trusts to figure any underpayment penalty.
• Form 2220 — the corporate equivalent of Form 2210.

Federal estimated tax due dates: tax year 2026

Individuals (Form 1040-ES)

Dates confirmed on the IRS second quarter and third quarter small business tax calendars for 2026.

Calendar-year C corporations

Corporate deposit dates confirmed on the IRS small business tax calendars for the second, third and fourth quarters of 2026.

Federal estimated tax due dates: tax year 2027

Individuals (Form 1040-ES)

Statutory due dates for tax year 2027 follow the standard Internal Revenue Code schedule set out in the IRS Estimated taxes guidance. The IRS applies a general rule across the tax calendar: if a due date falls on a Saturday, Sunday or legal holiday, the payment is on time if made the next day that is not a weekend or legal holiday.

Calendar-year C corporations

Statutory corporate installment dates for tax year 2027 are April 15, June 15, September 15 and December 15, 2027, under the same next-business-day rule.

How the four quarters work

Despite the name, the four periods are not even calendar quarters. The first installment covers three months (January to March), the second covers two months (April and May), the third covers three months (June to August) and the fourth covers four months (September to December). This is set out in the IRS estimated tax guidance.

Two safe-harbor tests for individuals

For individuals, the IRS generally considers you to have paid enough through withholding and estimated tax if you have paid at least 90% of this year’s tax or 100% of last year’s tax (110% if last year’s adjusted gross income was over $150,000), through a combination of withholding and timely installments. The exact figures and exceptions are in the IRS Estimated taxes page and Publication 505.

Illustrative example

A sole proprietor expects taxable net profit of $120,000 for tax year 2026 and has no W-2 withholding. Using illustrative round figures, their accountant works out total federal income tax plus self-employment tax of $30,000 for the year. Divided into four equal installments, that is $7,500 due on April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027. Actual numbers depend on deductions, credits and the owner’s full tax position; a CPA or qualified accountant should run the figures.

How Nella fits in

Nella is an AI finance assistant built by the accountants at AccTek Ltd. It connects read-only to QuickBooks or Xero and surfaces a federal filing calendar for calendar-year filers, so Form 1040-ES, 1120, 1120-S, 1065, 941, 944, 940 and W-2 dates sit next to the business’s own numbers. Nella does not calculate or file estimated tax; it points to the figures a CPA or qualified accountant will use. More detail is on the estimated taxes feature page.

Sources

• IRS: Estimated taxes
• IRS: Small business tax calendar u2013 second quarter 2026
• IRS: Small business tax calendar u2013 third quarter 2026
• IRS: Small business tax calendar u2013 fourth quarter 2026
• IRS: About Form 1040-ES

Nella provides financial information and education, not accounting or tax advice. Nella shows you the numbers. When a question needs professional judgment, such as a filing or a tax decision, Nella says so and points you to a qualified accountant.