Key Tax Deadlines for Small Business Owners in 2026

Updated for tax year 2025.

Curious about the business tax deadlines that you should mark on your calendar this tax season? Here’s what small business owners need to know.

Deadlines for filing small business tax returns

There are different filing deadlines to be aware of, depending on what type of business you have. Below are the key tax calendar dates to watch for in 2026.

Jan. 31, 2026

Deadline for any employees or independent contractors you hired last year (in 2024) to receive their W-2, 1099-NEC for nonemployees, or 1099-MISC tax forms.

March March 16, 2026 (due to March 15 falling on a weekend)

Deadline to file business income tax returns for partnerships, S corporations, or multi-member LLCs that are taxed as partnerships.

Note that this is the deadline for calendar year filers. While most taxpayers fall under this category, there are special exceptions for fiscal-year taxpayers. If your tax year doesn’t start on Jan. 1, you will instead follow the IRS fiscal year due date.

Deadline to file Form 2553 to switch your business entity to an S corporation (S corp) for tax year 2026. If you miss this deadline, your business will not be treated as an S corp until calendar year 2027.

April 15, 2026

Deadline for C corporations and LLCs taxed as corporations to file their corporate tax returns.

Deadline for sole proprietorships (Schedule C), single-member LLCs, and individuals to file their individual income tax returns.

Last day for you to make 2025 contributions to traditional and Roth IRAs. Traditional IRA contributions may help lower your taxable income if you meet IRS requirements.

Sept. 15, 2026

Deadline to file your partnership or S corporation return if you requested a tax extension.

Oct. 15, 2026

Deadline to file your sole proprietorship, multi-member LLC, or corporate return if you requested an extension.

2026 quarterly estimated tax payment deadlines

If you owe self-employment tax (Social Security and Medicare taxes) or receive any form of income that requires you to pay estimated taxes, here are the estimated tax due dates for 2026:

April 15, 2026 – Deadline for 2026 first quarter estimated tax payments

June 15, 2026 – Deadline for 2026 second quarter estimated tax payments

Sept. 15, 2026 – Deadline for 2026 third quarter estimated tax payments

Jan. 15, 2027 – Deadline for 2026 fourth quarter estimated tax payments

2025 quarterly estimated tax payment deadlines

April 15, 2025 – Deadline for 2025 first quarter estimated tax payments

June 16, 2025 – Deadline for 2025 second quarter estimated tax payments

Sept. 15, 2025 – Deadline for 2025 third quarter estimated tax payments

Jan. 15, 2026 – Deadline for 2025 fourth quarter estimated tax payments

Note: All quarterly tax payment deadlines typically fall on the 15th day of the month unless that date happens to be a weekend or a holiday. In this case, the payment deadline falls on the next business day instead.

How to file a tax extension as a small business owner

Not quite ready to file your federal income tax return yet? That’s okay — if you need more time, you have until your tax-filing deadline (March 16 or April 15, 2026, depending on your business structure) to apply for a tax-filing extension. An extension will give you an extra six months to file your return.

TaxAct® can help you request an extension or file your extended return if you have already asked for an extension.

Sole proprietors can request a tax extension using IRS Form 4868.

Partnerships, LLCs, S corps, and C corps can request an extension using IRS Form 7004.

Just remember, a tax extension only extends your federal tax return filing deadline, not your tax bill due date. You still need to pay any estimated tax payments or additional tax liability on your business’s tax deadline. Make sure to pay your estimated taxes on time and avoid underpayment to prevent owing any fees or penalties!

The bottom line

Staying on top of your business tax deadlines doesn’t have to be a headache. With TaxAct® Business, you can easily DIY your business taxes without being a certified CPA or tax professional. Our tax preparation software guides you through the entire tax filing process, including claiming business tax credits and tax deductions, making it straightforward for small business owners to file confidently and on time. Ready to get started? File your business taxes today with TaxAct and stay focused on what matters most — growing your business.

This article is for informational purposes only and not legal or financial advice.

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