Business Tax Deadlines 2026: Complete Filing Calendar

Key Takeaways

• Partnerships and S-Corps are due March 17, 2026 (moved from March 15 because it falls on Sunday). C-Corps and individuals are due April 15, 2026.
• Late filing penalties for partnerships and S-Corps are $220 per owner per month, even if no tax is due. A 5-partner LLC filed 3 months late faces $3,300 in penalties.
• Extensions extend your time to file, not your time to pay. Estimated taxes and any tax owed are still due by the original deadline.
• Texas franchise tax is due May 15, 2026, with an automatic extension to November 15 available by filing Form 05-164.
• Quarterly estimated tax payments are due April 15, June 15, September 15, and December 15 (for C-Corps) or January 15 of the following year (for individuals).

Missing a tax deadline costs money. For partnerships and S-Corps, late filing penalties are $220 per owner per month, regardless of whether you owe any tax. A 5-partner LLC that files 3 months late faces $3,300 in penalties before any other issues are even considered.

Business tax deadlines differ by entity type, and they’re earlier than most business owners expect. Partnerships and S-Corps are due in March, not April.

This calendar covers federal deadlines, extension deadlines, estimated tax payments, and Texas-specific dates for the 2025 tax year (filed in 2026). When a deadline falls on a weekend or holiday, the due date moves to the next business day.

2026 Federal Business Tax Deadlines at a Glance

Here’s the quick reference table for 2025 tax year returns filed in 2026:

Important note on 2026 dates: March 15, 2026 falls on a Sunday. This means partnership and S-Corp returns are due Monday, March 17, 2026 instead of the typical March 15 date.

Partnership Tax Deadlines (Form 1065)

Partnerships have the earliest filing deadline among common business entities.

Original Filing Deadline: March 17, 2026

Partnerships must file Form 1065 and issue Schedule K-1s to partners by the 15th day of the third month after the tax year ends. For calendar-year partnerships, this is normally March 15.

In 2026, because March 15 falls on a Sunday, the deadline moves to Monday, March 17, 2026.

What’s due by March 17:

• Form 1065 (U.S. Return of Partnership Income)
• Schedule K-1 for each partner showing their share of income, deductions, and credits
• State partnership returns for any state where you have filing requirements

Partners need their K-1s to file their personal returns. Late K-1 delivery means your partners may need to file extensions for their personal taxes.

Extension Deadline: September 15, 2026

File Form 7004 by March 17, 2026 to get an automatic 6-month extension, pushing your deadline to September 15, 2026.

Critical point: The extension extends your time to file, not your time to pay. Partners still owe estimated taxes on their share of partnership income by the original due dates.

For complete guidance on extensions, see our business tax extension deadlines guide.

Late Filing Penalty

The penalty for late partnership returns is $220 per partner per month (or partial month), for up to 12 months.

Example: A 5-partner LLC that files 3 months late faces: $220 × 5 partners × 3 months = $3,300 in penalties

This penalty applies even if no tax is due. Partnerships don’t pay tax at the entity level, but the late filing penalty still applies.

For comprehensive partnership tax guidance, see our Complete Guide to Partnership Taxation.

S-Corporation Tax Deadlines (Form 1120-S)

S-Corporations share the same filing deadline as partnerships but have additional payroll-related obligations.

Original Filing Deadline: March 17, 2026

S-Corps file Form 1120-S and issue Schedule K-1s to shareholders by the 15th day of the third month after year end. For calendar-year S-Corps, this is normally March 15.

In 2026, the deadline is Monday, March 17, 2026.

What’s due by March 17:

• Form 1120-S (U.S. Income Tax Return for an S Corporation)
• Schedule K-1 for each shareholder
• State S-Corp returns for any state with filing requirements
• W-2s for officers (should already have been issued by January 31)

Extension Deadline: September 15, 2026

File Form 7004 by March 17 for an automatic 6-month extension.

Late Filing Penalty

The penalty structure mirrors partnerships: $220 per shareholder per month (or partial month), up to 12 months.

Other S-Corp Tax Dates to Remember

S-Corp shareholder-employees must receive reasonable salaries with proper W-2 reporting. For details on S-Corp tax deadlines and filing requirements, see our dedicated guide.

C-Corporation Tax Deadlines (Form 1120)

C-Corporations have a later filing deadline than pass-through entities but face estimated tax requirements throughout the year.

Original Filing Deadline: April 15, 2026

C-Corps file Form 1120 by the 15th day of the fourth month after year end. For calendar-year C-Corps, this is April 15, 2026.

What’s due by April 15:

• Form 1120 (U.S. Corporation Income Tax Return)
• State corporate returns for states with filing requirements
• First quarter estimated tax payment for 2026

Extension Deadline: October 15, 2026

File Form 7004 by April 15 for an automatic 6-month extension.

Important: C-Corporations must pay estimated taxes quarterly. The extension doesn’t extend your time to pay. You’re still responsible for paying by the original deadline to avoid underpayment penalties.

C-Corp Estimated Tax Due Dates (Calendar Year 2026)

C-Corps must pay estimated taxes quarterly if they expect to owe $500 or more:

For more details, see our guide to C-Corp tax filing deadlines and requirements.

Single-Member LLC and Sole Proprietor Deadlines

Single-member LLCs (not electing S-Corp treatment) and sole proprietors have the simplest filing structure.

Schedule C (Part of Form 1040)

Single-member LLCs and sole proprietors report business income on Schedule C, which attaches to the individual Form 1040.

Original Deadline: April 15, 2026 Extension Deadline: October 15, 2026 (with Form 4868)

Self-Employment Tax and Estimated Payments

Self-employed individuals must pay estimated taxes quarterly if they expect to owe $1,000 or more:

Underpayment penalty: If you don’t pay enough through estimates or withholding, you’ll owe an underpayment penalty plus interest.

Safe harbor rules: You can avoid underpayment penalties by paying:

• 100% of prior year tax (110% if your income exceeded $150,000), OR
• 90% of current year tax

Single-Member LLC with S-Corp Election

If your single-member LLC elected S-Corp treatment by filing Form 2553, you follow S-Corp deadlines, not Schedule C deadlines.

Key dates for single-member LLCs taxed as S-Corps:

• Form 1120-S due: March 17, 2026
• W-2 to yourself: January 31, 2026
• Extension deadline: September 15, 2026

The S-Corp election changes everything about your filing requirements. You must pay yourself a reasonable salary, file a separate corporate return, and issue yourself a K-1 for pass-through income.

For guidance on making this election, see our guide on converting an LLC to an S-Corp.

Information Return Deadlines

Beyond the main business returns, you have information return obligations for payments to employees and contractors.

Penalties for late information returns:

• $60 per form if filed within 30 days of due date
• $120 per form if filed more than 30 days late but by August 1
• $310 per form if filed after August 1 or not filed at all
• $630 per form for intentional disregard (no maximum)

For detailed guidance on contractor payments, see our 1099 filing guide.

Texas Franchise Tax Deadlines

Texas businesses face an additional filing obligation. While Texas has no corporate income tax, it imposes a franchise tax (margin tax) on most business entities.

Original Deadline: May 15, 2026

The Texas franchise tax return and payment are due May 15 for the prior year’s activity.

Extension Deadline: November 15, 2026

File Form 05-164 by May 15 for an automatic extension to November 15, 2026.

To avoid penalties, you must pay either:

• 90% of the tax due, OR
• 100% of prior year’s tax

Who Must File Texas Franchise Tax

Nearly every business entity in Texas must file:

• Corporations (C and S)
• LLCs (including single-member LLCs)
• Partnerships and LLPs
• Professional corporations and associations

No Tax Due Threshold (2026)

Entities with total revenue at or below the no-tax-due threshold (currently $2.47 million, verify annually for updates) file a No Tax Due Report instead of paying tax.

Even if you owe no tax, you must still file the report to maintain good standing with the Texas Comptroller.

Extension Filing Deadlines Summary

Extensions give you more time to file but don’t extend your time to pay. Here’s the complete extension reference:

For complete extension guidance, see our business tax extension deadlines guide.

What Happens If You Miss a Deadline

Understanding the penalties helps prioritize when deadlines approach.

Partnership/S-Corp Late Filing Penalty

$220 per owner/shareholder per month (or partial month), up to 12 months. This penalty applies even if no tax is due.

Example calculation: 3-partner LLC files 2 months late = $220 × 3 × 2 = $1,320

C-Corporation Late Filing Penalty

5% of unpaid tax per month, up to 25% maximum.

Minimum penalty for returns over 60 days late: the lesser of $485 or 100% of tax due.

Failure to Pay Penalty

0.5% of unpaid tax per month, up to 25% maximum. This runs concurrently with the failure to file penalty.

Interest

Interest accrues on unpaid tax at the federal short-term rate plus 3%, compounded daily. The rate changes quarterly.

For guidance on dealing with tax debt, see our guide on IRS payment plans.

2026 Business Tax Calendar (Complete Month-by-Month)

Print this calendar or add these dates to your planning system.

January 2026

• January 15: Q4 2025 individual estimated tax payment due
• January 31: W-2s and 1099-NECs due to recipients AND to the IRS

February 2026

• February 28: Paper 1099-MISC/1099-K due to IRS (e-file deadline is March 31)

March 2026

• March 17: Partnership returns (Form 1065) due
• March 17: S-Corporation returns (Form 1120-S) due
• March 17: Extension requests (Form 7004) due for partnerships and S-Corps
• March 31: E-file deadline for 1099-MISC/1099-K to IRS

April 2026

• April 15: C-Corporation returns (Form 1120) due
• April 15: Individual returns (Form 1040) due
• April 15: Q1 2026 estimated tax due (all entities)
• April 15: Extension requests due for C-Corps (Form 7004) and individuals (Form 4868)

May 2026

• May 15: Texas franchise tax due

June 2026

• June 15: Q2 2026 estimated tax due

September 2026

• September 15: Extended partnership returns due
• September 15: Extended S-Corp returns due
• September 15: Q3 2026 estimated tax due

October 2026

• October 15: Extended C-Corp returns due
• October 15: Extended individual returns due

November 2026

• November 15: Extended Texas franchise tax due

December 2026

• December 15: Q4 2026 C-Corp estimated tax due

Set Up Your Tax Calendar for Success

Deadlines become emergencies when you’re not prepared. Here’s how to stay ahead:

1. Add deadlines to your calendar 30 days in advance

Set reminders that give you time to gather documents and address issues, not just last-minute alerts.

2. Set document-gathering reminders 60 days before filing deadlines

For March 17 deadlines, start gathering documents in mid-January. This gives you time to request missing 1099s and resolve questions.

3. Work with your CPA to determine if extensions make sense

Extensions aren’t always the best choice. They delay K-1 delivery to owners, which can cascade into personal return extensions. Sometimes pushing to meet the original deadline is worth the effort.

4. Automate quarterly estimated payments

Set up automatic payments through IRS Direct Pay or EFTPS to avoid missing quarterly deadlines. One missed estimated payment can trigger penalties for the entire year.

5. Mark the Texas franchise tax deadline separately

Many business owners forget about franchise tax because it falls outside the normal March/April filing season. May 15 catches people off guard.

Understanding and tracking business tax deadlines prevents costly penalties and keeps your business in good standing. For federal income tax deadlines beyond business returns, see our comprehensive deadline reference.

If you need help managing your business tax deadlines, we track deadlines and send reminders so you don’t have to scramble every filing season.

Frequently Asked Questions

When are S-Corp taxes due in 2026?

S-Corp returns (Form 1120-S) are due March 17, 2026 for calendar-year corporations. The deadline is normally March 15, but in 2026 that falls on a Sunday, moving the deadline to Monday, March 17. With an extension, the deadline becomes September 15, 2026.

What’s the penalty for filing a partnership return late?

The late filing penalty for partnerships is $220 per partner per month (or partial month), up to 12 months. This applies even if the partnership owes no tax. A 4-partner LLC that files 2 months late faces $1,760 in penalties.

Do I need to pay taxes by the extension deadline?

No. Extensions extend your time to file, not your time to pay. You should pay any tax owed by the original deadline (March 17 for partnerships/S-Corps, April 15 for C-Corps and individuals) to avoid interest and penalties.

When is Texas franchise tax due?

Texas franchise tax is due May 15 each year. An automatic extension to November 15 is available by filing Form 05-164, but you must pay at least 90% of tax due or 100% of prior year tax to avoid penalties.

What forms do I need to file an extension?

Partnerships, S-Corps, and C-Corps file Form 7004 for automatic 6-month extensions. Individuals and sole proprietors file Form 4868. Texas franchise tax extensions require Form 05-164.