When Are Business Taxes Due? Deadlines Every Business Owner Should Know in 2026

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Business tax due dates depend on your business structure, with most annual returns due between March and April — plus quarterly estimated tax deadlines throughout the year. Missing the deadline can trigger penalties and interest, even if you ultimately owe little or no tax.

Below is a clear, by-business-type breakdown of when returns are due, who actually pays the tax and how to stay compliant in 2026, including a simple deadline reference you can bookmark.

Business Tax Deadlines by Business Type in 2026

Understanding your filing deadline starts with knowing how your business is legally structured. The IRS treats each entity type differently, which affects both when paperwork is due and who pays the tax.

Sole Proprietors and Single-Member LLCs

Typical deadline: April 15, 2026 — or the next business day, if applicable

If you operate as a sole proprietor or a single-member LLC that hasn’t elected corporate tax treatment, your business income is reported on your personal tax return using Schedule C attached to Form 1040, according to the IRS’s guidance on Schedule C.

Because the business itself doesn’t file a separate income tax return, the filing deadline matches your personal tax deadline. The IRS confirms that individual tax returns are generally due in mid-April each year, unless the date falls on a weekend or federal holiday, in which case the deadline shifts to the next business day, per the IRS’s When to File Your Taxes page.

If you expect to owe at least $1,000 in tax for the year after credits and withholding, you generally must make quarterly estimated tax payments. The IRS explains that estimated taxes apply to income that isn’t subject to withholding, including self-employment income, on its Estimated Taxes resource.

Partnerships and Multi-Member LLCs

Typical deadline: March 15, 2026

Partnerships and multi-member LLCs taxed as partnerships must file an informational return using Form 1065, even though the business itself typically doesn’t pay federal income tax. The IRS describes Form 1065 as a way to report income, deductions and other financial information for the partnership in its About Form 1065 guidance.

Instead of paying tax at the entity level, profits and losses pass through to each owner. Partners receive a Schedule K-1, which shows their share of income and deductions that must be reported on their personal tax returns, according to the IRS’s Schedule K-1 overview.

This earlier deadline exists so partners can receive their K-1 forms in time to prepare their own individual returns by April.

S Corporations

Typical deadline: March 15, 2026.

S corporations also operate as pass-through entities for federal tax purposes. The corporation files Form 1120-S to report income, deductions and credits, but the business itself generally doesn’t pay federal income tax. The IRS outlines S corporation filing requirements in its About Form 1120-S documentation.

Shareholders receive Schedule K-1 forms showing their portion of income and losses. Those amounts flow through to each owner’s personal tax return, consistent with the IRS’s explanation of S corporations.

Even if the company keeps profits in the business bank account, shareholders still owe tax on their allocated income.

C Corporations

Typical deadline: April 15, 2026 for calendar-year corporations.

C corporations are taxed separately from their owners. The business files Form 1120 and pays corporate income tax directly at the entity level. The IRS confirms filing requirements and due dates on its About Form 1120 page.

Corporations that operate on a fiscal year rather than a calendar year generally file by the 15th day of the fourth month after their tax year ends, as explained in the IRS’s broader guidance on corporations.

Dividends paid to shareholders may also be taxable at the individual level.

Quick Reference: Business Tax Deadlines

This separation between who files paperwork and who actually pays tax is one of the most common sources of confusion for business owners.

Quarterly Estimated Taxes: What Businesses Often Miss

Many business owners focus on annual filing deadlines but overlook quarterly estimated taxes — which is where penalties often arise.

Who Has To Pay Estimated Business Taxes

The IRS explains that estimated tax payments are required when income is not subject to withholding, including self-employment income, investment income and pass-through business income, on its Estimated Taxes page.

This typically applies to:

• C corporations that expect to owe at least $500 in tax for the year
• Sole proprietors and independent contractors
• Partners and S corporation shareholders

Estimated Tax Due Dates

• April 15
• June 15
• September 15
• January 15 of the following year, according to the IRS’s Form 1040-ES instructions.

Why Missing These Deadlines Triggers Penalties

The U.S. tax system operates on a pay-as-you-go basis. The IRS states that taxpayers are expected to pay tax as income is earned throughout the year, not simply at filing time, in its guidance on Pay As You Go.

If you wait until April to pay everything, you may still owe underpayment penalties — even if your total tax bill is paid in full by the filing deadline. Penalties are calculated based on when payments were made during the year, not just the final balance.

What Happens if You Miss a Business Tax Deadline?

Missing a deadline doesn’t automatically mean severe consequences, but penalties and interest can add up quickly if the issue isn’t addressed.

Late Filing vs. Late Payment

Filing late and paying late are separate issues under IRS rules. The IRS assesses different penalties depending on whether the return itself is late or whether the tax remains unpaid, as explained on its Penalties page.

Filing on time — even without full payment — generally reduces exposure to the more severe failure-to-file penalty.

Common IRS Penalties To Know

• Failure-to-file penalty: Typically the largest penalty when returns are late.
• Failure-to-pay penalty: Charged when tax remains unpaid after the due date.
• Interest: Accrues on unpaid balances until fully paid, according to the IRS’s Interest guidance.

When Extensions Help — and When They Don’t

An extension gives you more time to file paperwork, not more time to pay taxes owed. The IRS makes this distinction clear in its Extension of Time to File guidance.

Any unpaid tax should still be paid by the original due date to minimize penalties and interest. Estimated tax requirements continue to apply even if you file an extension.

Key Business Tax Deadlines To Bookmark Each Year

Keeping a simple annual checklist reduces last-minute stress and costly mistakes.

Annual Deadlines at a Glance

• March 15: Partnerships and S corporations
• April 15: Sole proprietors and C corporations
• Quarterly estimated taxes: April 15, June 15, September 15 and January 15 (following year)

How To Avoid Missing Deadlines

• Set calendar reminders at least two to three weeks ahead of each deadline
• Keep business accounting separate from personal finances
• Review estimated tax obligations midyear instead of waiting until tax season
• Consider working with a qualified tax professional when income fluctuates or the business structure changes.

Karen Doyle contributed to the reporting of this article.

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