Business Tax Deadlines for 2026: What Corporations and LLCs need to know?

Understanding business tax deadline requirements is critical for staying compliant. Missing important dates can result in penalties, interest charges and financial stress.

This guide covers all the essential corporate tax deadlines, and LLC filing deadline dates for 2026. Whether you run a corporation, S corp, partnership or LLC, you’ll find everything you need to know about the business tax deadlines.

Key takeaways

• Mark key tax dates: March 16 (S corps/partnerships) and April 15 (C corps/sole proprietors).
• File Form 7004 or Form 4868 on time to extend filing, not payment.
• Track quarterly estimated payments: April 15, June 15, September 15 and January 15.
• Remember that payroll and information return deadlines (W-2, 1099) fall on January 31, 2026, and the updated Q4 payroll tax deadline is February 2, 2027.
• Keep records organised and coordinate with a CPA early for strategic tax planning.
• Confirm state-specific filing dates, as they often differ from IRS due dates.
• Meeting deadlines builds financial credibility, avoids costly penalties, and preserves business cash flow.

What are different business tax filing deadlines for each entity?

The business tax deadlines varies depending on your company structure. Each entity type has specific due dates and requirements that you must follow.

Partnership & LLC tax deadlines

Partnerships and multi-member LLCs typically file as pass-through entities. They must report income using Form 1065.

Partnership filing deadline: March 16, 2026

This is when partnership tax returns are due. The IRS requires partnerships to submit Form 1065 by this date for the 2025 tax year.

Pass-through entities do not pay tax at the entity level. Instead, they distribute profits and losses to partners or members through Schedule K-1 forms.

Extension available: You can file Form 7004 to get an automatic extension. This moves your filing deadline for corporate tax returns to September 15, 2026.

However, the extension only gives you more time to file. It doesn’t extend the time to pay taxes owed.

S Corporation tax filing deadlines

S corporations follow the same schedule as partnerships. They must file Form 1120-S by the March deadline.

S Corp tax return due date: March 16, 2026

The S corp tax return extension due date is September 15, 2026. You must file Form 7004 by March 16 to receive this extension.

S corps are also pass-through entities. They issue Schedule K-1s to shareholders showing their share of income, deductions, and credits.

If an LLC elects S corp status, when must it file taxes? The answer is March 16, following the S corporation schedule.

C Corporation tax deadlines

C corporations have different filing requirements. They face double taxation because the corporation pays tax on profits.

C Corporation tax deadline: April 15, 2026

This is the due date to file LLC tax return if your LLC elected C corp status. Standard C corps must submit Form 1120 by this date.

The corporate tax due date is the 15th day of the fourth month after the fiscal year ends. Most calendar-year corporations use December 31 as their year-end.

Extension deadline: October 15, 2026

File Form 7004 by April 15 to receive this extension. Remember that the business tax extension deadline only affects filing, not payment.

Sole Proprietorship & Single Member LLC deadlines

Sole proprietors and single-member LLCs file with their personal tax returns. They use Schedule C attached to Form 1040.

Filing deadline: April 15, 2026

This company tax filing deadline matches individual tax day. Single-member LLCs are treated as disregarded entities by default.

When do LLC file taxes if you’re a single owner? The LLC tax date follows the personal tax deadline unless you elect corporate taxation.

Extension available: File Form 4868 by April 15. This extends your deadline to October 15, 2026.

Complete business tax calendar 2026

Here’s a comprehensive table showing all critical dates for when taxes are due for LLC and corporation entities:

Quarterly estimated tax payment schedule

Business taxes due throughout the year include quarterly estimated payments. These are required if you expect to owe significant taxes.

Who must pay quarterly taxes?

C corporations must pay if they expect to owe $500 or more. S corporations, partnerships, and sole proprietors must pay if they expect to owe $1,000 or more.

Estimated tax due dates in 2026

The business tax filing deadline for quarterly payments follows this schedule:

First quarter (January-March 2026)

• Payment Due: April 15, 2026
• Covers income earned from January 1 through March 31

Second quarter (April-May 2026)

• Payment Due: June 15, 2026
• Covers income earned from April 1 through May 31

Third quarter (June-August 2026)

• Payment Due: September 15, 2026
• Covers income earned from June 1 through August 31

Fourth quarter (September-December 2026)

• Payment Due: January 15, 2027
• Covers income earned from September 1 through December 31

Missing these deadlines can trigger underpayment penalties. The IRS charges interest on late payments regardless of whether you filed an extension.

Payroll tax deadlines for employers

If you have employees, additional filing requirements apply. These deadlines are critical for compliance.

Form 941: Quarterly Payroll tax returns

Form 941 reports federal income tax, Social Security, and Medicare taxes withheld from employee paychecks. These are called FICA taxes.

Q1 2026 (January-March): Due April 30, 2026
Q2 2026 (April-June): Due July 31, 2026
Q3 2026 (July-September): Due November 2, 2026
Q4 2026 (October-December): Due February 2, 2027

Small employers with annual tax liability of $1,000 or less may qualify to file Form 944 annually instead of quarterly Form 941.

FICA tax deposits

You must deposit FICA taxes on a monthly or semiweekly schedule. This depends on your total employment tax liability.

Monthly Depositors: Businesses that paid $50,000 or less in employment taxes make deposits by the 15th of the following month.

Semiweekly Depositors: Businesses that paid more than $50,000 deposit taxes within three to five business days of the payroll date.

All federal tax deposits must be made electronically using the Electronic Federal Tax Payment System (EFTPS).

Electronic filing: TCC and FIRE System

Businesses filing 10 or more information returns must file electronically. To do so, you must:

• Obtain a Transmitter Control Code (TCC) from the IRS by applying through the Filing Information Returns Electronically (FIRE) system.
• The deadline to request a TCC for the 2026 tax year was November 1, 2025.
• The FIRE system enables electronic submission of W-2s, 1099s, and other information returns.

Form 940: Federal unemployment tax

Form 940 reports Federal Unemployment Tax Act (FUTA) taxes. The deadline varies based on your liability.

If your FUTA tax liability exceeds $500 for the calendar year, you must make quarterly payments. Quarterly deadlines fall on the last day of the month after each quarter ends.

If your total FUTA liability is $500 or less, you can pay with your Form 940 by January 31.

Employee & Contractor information returns

By January 31 of each year, you must provide W-2 forms to employees and 1099-NEC forms to independent contractors.

These forms report compensation paid during the previous year. You must also file copies with the IRS by the same date.

Late filing penalties start at $60 per form if you’re 30 days late. The penalty increases based on how late you file.

What tax forms do I need to file for an LLC?

The tax forms LLC owners need depend on how the IRS classifies your business. LLCs have flexibility in tax treatment.

Default LLC classifications

Single-member LLC: Treated as a sole proprietorship by default. File Schedule C with Form 1040.

Multi-member LLC: Treated as a partnership by default. File Form 1065 and issue Schedule K-1s to members.

Electing different tax status

LLCs can elect to be taxed as corporations. This changes both your filing deadline for LLC and the forms you use.

Electing S Corporation status: File Form 2553. You must file by March 17, 2025, for the election to take effect in 2025.

If you file after this date, the election won’t take effect until 2026. The deadline for LLCs electing S corp status is March 16, 2026.

Electing C Corporation status: File Form 8832. Once approved, your LLC taxes due date shifts to April 15, following C corp rules.

Fiscal year vs. Calendar year deadlines

Most businesses use a calendar year (January 1 to December 31). However, some operate on a fiscal year basis.

Fiscal year filing rules

C Corporations: File by the 15th day of the fourth month after the fiscal year ends.

For example, if your fiscal year ends October 31, your deadline is February 15. The exception is fiscal years ending June 30, which have a September 15 deadline.

S Corporations and Partnerships: File by the 15th day of the third month after the fiscal year ends.

If your fiscal year ends September 30, your deadline is December 15.

Estimated tax payments for Fiscal year filers

Fiscal year taxpayers have different quarterly payment dates:

• 15th day of the fourth month of the fiscal year
• 15th day of the sixth month of the fiscal year
• 15th day of the ninth month of the fiscal year
• 15th day of the first month after the fiscal year ends

How business tax extensions work?

Extensions provide more time to file but not to pay. Understanding this distinction prevents penalties.

Extension deadlines by entity type

Partnerships and S Corporations: File Form 7004 by March 16. This extends your deadline to September 15.

C Corporations: File Form 7004 by April 15. This extends your deadline to October 15.

Sole Proprietors: File Form 4868 by April 15. This extends your deadline to October 15.

Payment requirements

Any tax owed must still be paid by the original deadline. Interest and penalties accrue on unpaid balances after the due date.

Even with an extension in place, late payment penalties apply. The penalty is typically 0.5% of the unpaid amount per month.

Common tax filing mistakes to avoid

Many business owners make preventable errors. These mistakes trigger penalties and IRS notices.

Confusing filing extensions with payment extensions

An extension gives you more time to file paperwork. It does not extend the payment deadline.

Calculate and pay your estimated tax liability by the original due date. This prevents interest charges.

Overlooking quarterly estimated payments

Missing quarterly payments triggers underpayment penalties. These penalties apply even if you ultimately file on time.

Set reminders for all four quarterly deadlines. Make payments even if you plan to file an extension.

Assuming State deadlines match Federal deadlines

Most states have their own corporate filing requirements. Some align with federal deadlines, but many don’t.

Check your state’s specific due dates annually. You may need to file additional forms like franchise tax or net worth tax returns.

Misapplying deadlines across entity types

S corporation and C corporation deadlines differ significantly. Using the wrong date can result in late filing penalties.

The taxes due march 15 deadline (actually March 16 in 2026) applies only to partnerships and S corps. C corporations file on April 15.

Not adjusting for weekends and holidays

When a deadline falls on a weekend or legal holiday, it shifts to the next business day.

Federal holidays include all government holidays plus any legal holiday in the District of Columbia. Always verify the actual due date.

Preparation best practices

Staying ahead of deadlines requires planning and organization. These practices help ensure compliance.

Close financial records early

Reconcile all accounts, payroll, and equity changes before the filing deadline. Aim to close your books at least one month before taxes are due.

Early preparation gives your accountant time to identify issues and plan tax-saving strategies.

Forecast taxable income

Use financial projections to estimate quarterly tax payments. Accurate estimates prevent underpayment penalties.

Review your projections quarterly and adjust payments as needed. Business income can fluctuate significantly throughout the year.

Coordinate with your CPA early

Provide financial statements and tax documentation well before deadlines. Last-minute rushes increase the risk of errors.

Schedule a planning meeting with your CPA in January or February. Discuss strategies for the current year and review prior-year issues.

Maintain organized records

Keep detailed records of all income, expenses, and tax payments. Digital accounting software simplifies this process.

Store receipts, invoices, and bank statements in an organized system. Good recordkeeping supports deductions and helps defend against audits.

Confirm state filing obligations

Each state has separate due dates and electronic filing requirements. Don’t assume state deadlines match federal deadlines.

Some states require franchise taxes, gross receipts taxes, or other filings beyond income tax returns.

Why timely filing matters?

Meeting tax deadlines demonstrates sound corporate governance. It maintains good standing with the IRS and state agencies.

How much late filing penalty cost?

Late filing penalties start at 5% of unpaid taxes per month. The penalty caps at 25% of the total tax due.

Late payment penalties are typically 0.5% per month. Interest also accrues on unpaid balances.

Combined, these charges quickly add up. A $10,000 tax bill could grow by thousands of dollars in just a few months.

Maintaining credibility

For corporations with investors or lenders, consistent compliance reinforces credibility. It demonstrates financial discipline and responsible management.

Public companies and businesses seeking funding face extra scrutiny. Tax compliance is a key factor in due diligence reviews.

Preserving cash flow

Penalties and interest drain cash that could support operations or growth. Timely filing helps maintain a strong cash position.

For startups especially, avoiding unnecessary expenses is critical. Every dollar saved strengthens your runway.

State tax considerations

In addition to federal deadlines, businesses must comply with state requirements. These vary significantly by jurisdiction.

State income tax returns

Most states impose corporate income taxes. Some align with federal deadlines, while others set independent due dates.

States like Texas and Wyoming have no corporate income tax. However, they may have franchise taxes or other business levies.

Franchise and net worth taxes

Some states require annual franchise tax returns. These are often due on different dates than income tax returns.

Delaware franchise tax, for example, is due March 1 for corporations. The calculation method differs from income tax.

Sales and use tax returns

Businesses that sell products or certain services must file sales tax returns. Filing frequency depends on sales volume.

High-volume businesses file monthly. Smaller businesses may file quarterly or annually. Each state sets its own thresholds and deadlines.

Partnership & Corporate tax preparation

The complexity of returns varies by entity type. Understanding requirements helps you prepare effectively.

Partnership tax returns (Form 1065)

Partnerships report income, deductions, gains, and losses. The partnership itself doesn’t pay tax.

Instead, each partner receives a Schedule K-1. This form shows their share of partnership items for reporting on personal returns.

The due date to file LLC tax return as a partnership is March 16. Partners need their K-1s to complete personal returns by April 15.

S Corporation tax returns (Form 1120-S)

S corps also issue Schedule K-1s to shareholders. The corporation reports income and deductions but doesn’t pay federal income tax.

Shareholders report their share of income on personal returns. They pay tax at individual rates.

The filing deadline for corporate tax returns structured as S corps is March 16. This timing allows shareholders to file personal returns on time.

C Corporation tax returns (Form 1120)

C corps pay tax at the corporate level. Shareholders pay tax again on dividends received, creating double taxation.

However, C corps have more flexibility in deducting expenses and benefits. They can also retain earnings without immediate shareholder taxation.

The extension deadline for corporate tax returns is October 15 when using Form 7004.

Tax credits and planning opportunities

Strategic tax planning goes beyond meeting deadlines. Consider these opportunities to reduce your tax burden.

Research & Development Credits

The R&D tax credit rewards businesses that innovate. Qualifying activities include developing new products, processes, or software.

The credit can offset both income tax and payroll tax. Startups can claim up to $500,000 against payroll tax annually.

Eligible expenses include wages, supplies, and contract research related to qualified research activities. It can offset income tax and, for startups, some payroll taxes. Claim this credit using IRS Form 6765. More details can be found on the IRS R&D Tax Credit page.

Qualified small business stock (QSBS)

C corporations may qualify for QSBS treatment under Section 1202. This allows founders and investors to exclude capital gains when selling stock.

To qualify, the corporation must meet specific requirements. These include operating an active business and maintaining gross assets under $50 million.

The exclusion can save millions in taxes. However, strict rules apply, so consult a tax advisor.

Section 179 & bonus depreciation

Businesses can immediately deduct equipment purchases under Section 179. The 2026 limit is expected to be around $1.2 million.

Bonus depreciation allows additional first-year deductions. These provisions help reduce current-year tax liability.

When to seek professional help?

Tax compliance is complex and constantly changing. Professional guidance can save money and prevent costly mistakes.

Signs you need a tax professional

Consider hiring help if you:

• Have multiple business entities or locations
• Operate in multiple states
• Have employees or significant payroll
• Recently changed your business structure
• Face complex transactions like mergers or equity compensation
• Lack time to stay current on tax law changes

Choosing the right advisor

Look for a CPA or enrolled agent with business tax experience. Industry-specific knowledge is valuable.

Ask about their approach to tax planning, not just compliance. Proactive advisors identify savings opportunities throughout the year.

Year round tax planning

The best tax strategies involve year-round planning. Don’t wait until tax season to think about optimization.

Schedule quarterly reviews with your advisor. Discuss estimated payments, potential deductions, and strategic decisions.

Technology tools for tax management

Modern accounting software simplifies tax compliance. These tools help track deadlines and organize records.

Accounting software features

Look for software that:

• Tracks income and expenses automatically
• Generates financial reports
• Integrates with bank accounts
• Supports multiple entities
• Provides tax deadline reminders
• Facilitates CPA collaboration

Popular options include QuickBooks, Xero, and FreshBooks. Many integrate with tax preparation software.

Electronic filing requirements

Businesses filing 10 or more information returns must file electronically. This includes W-2s and 1099s.

You’ll need a Transmitter Control Code (TCC) from the IRS. Apply through the Filing Information Returns Electronically (FIRE) system.

The deadline to request a TCC for the 2026 tax filing year was November 1, 2025. Plan ahead for future years.

Conclusion

Understanding tax deadlines prevents penalties and maintains compliance. Whether you operate a C corporation, S corp, partnership, or LLC, marking these dates on your calendar is essential.

The corporate tax deadlines for 2026 fall on March 16 for partnerships and S corps. C corporations and sole proprietors file by April 15.

Don’t forget quarterly estimated tax payments throughout the year. These deadlines apply to most business structures and help you avoid underpayment penalties.

Working with a qualified CPA or tax professional can save time and money. They help identify deductions, ensure accuracy, and provide strategic guidance.

Start preparing now for a smooth 2026 tax season. Organization and proactive planning make the process less stressful and more efficient.

FAQs about Business Tax Deadlines