Important Tax Deadlines Every Small Business Must Know in 2025/2026
Tax compliance is a crucial part of running a small business in the United States. Missing important deadlines can lead to penalties, interest charges, and unnecessary stress. Whether you are a sole proprietor, partnership, corporation, or have employees, understanding key tax deadlines helps you plan ahead, stay compliant, and manage your cash flow effectively.
In 2025 and 2026, there are several major federal tax deadlines small business owners should know. This guide breaks them down by type of tax obligation and provides practical planning advice that can help you avoid last-minute rushes and costly mistakes.
Filing Your Federal Business Income Tax Returns
April 15, 2025 – Tax Year 2024 Returns Due
For most small businesses operating with a calendar year, federal income tax returns for 2024 are due on April 15, 2025. This applies to:
Sole proprietors reporting income on Schedule C of Form 1040
C corporations filing Form 1120
Individuals reporting business income as part of personal returns
If you need more time, you can file an extension using Form 4868, generally extending your filing deadline to October 15, 2025. However, an extension to file is not an extension to pay any tax owed.
March 16, 2026 – 2025 Tax Returns for Partnerships and S Corporations
Businesses taxed as partnerships (including multi-member LLCs) and S corporations must file their 2025 federal tax returns by March 16, 2026. They use Form 1065 (partnerships) or Form 1120-S (S corporations) and must furnish Schedule K-1s to partners or shareholders by this date.
April 15, 2026 – 2025 Tax Returns for C Corporations and Individuals
For tax year 2025, the general filing deadline for:
C corporations (Form 1120)
Individuals reporting business income (sole proprietors, single-member LLCs)
is April 15, 2026.
If you file for an extension with Form 7004 (corporations) or Form 4868 (individuals), you have until October 15, 2026 to submit the return.
Quarterly Estimated Tax Payments
The U.S. tax system generally operates on a pay-as-you-go basis. If you expect to owe tax of $1,000 or more when your return is filed, you are usually required to pay estimated taxes quarterly. This applies to sole proprietors, partners, S corporation shareholders, and others without tax withholding that covers their full liability.
Estimated Payments for Tax Year 2025
For the 2025 tax year, estimated tax payments are due on:
April 15, 2025 – 1st quarter
June 16, 2025 – 2nd quarter
September 15, 2025 – 3rd quarter
January 15, 2026 – 4th quarter
Estimated Payments for Tax Year 2026
For the 2026 tax year, payments generally are:
April 15, 2026 – 1st quarter
June 15, 2026 – 2nd quarter
September 15, 2026 – 3rd quarter
January 15, 2027 – 4th quarter
Estimated payments are made using Form 1040-ES for individuals and sole proprietors and Form 1120-W for corporations. Late or insufficient payments can result in penalties.
Payroll Tax and Information Return Deadlines
Small businesses with employees must also meet regular payroll tax deposit and return deadlines.
January 31 – W-2 and 1099 Reporting
Each year by January 31, you must:
Provide W-2 forms to employees and file them with the Social Security Administration
Provide and file 1099-NEC forms to report payments of $600 or more to independent contractors
If this date falls on a weekend or holiday, the deadline typically moves to the next business day.
Quarterly Payroll Tax Filings
Employers generally file Form 941 quarterly to report income taxes, Social Security, and Medicare taxes withheld. Typical deadlines for these quarterly filings include:
April 30
July 31
October 31
January 31 (following year)
This timeline helps small business owners plan cash flow and ensure timely deposits. Accurate payroll reporting also supports compliance with both federal and state tax requirements.
Extensions and Special Situations
Extension Filing Deadlines
Filing an extension gives you extra time to prepare your return, but it does not extend the time to pay taxes owed. For most small businesses:
October 15, 2025 – Extended deadline for 2024 returns
October 15, 2026 – Extended deadline for 2025 returns
Filing extension forms on time is essential to avoid late-filing penalties.
State and Local Tax Considerations
In addition to federal deadlines, your business may have state or local filing obligations. These vary by state and can include income tax, franchise tax, and sales tax deadlines. State deadlines often align with federal deadlines, but exceptions exist depending on law changes and relief provisions.
For example, some states that experienced natural disasters in 2025 received extended filing deadlines up to November 2025 for affected taxpayers, including businesses. Always check your state’s department of revenue for updates.
Why Keeping Good Records Matters
Meeting deadlines starts with organized financial records. Accurate bookkeeping helps you track income, expenses, and payments in real time. It also ensures you have the necessary documentation if you are asked to verify your filings or deductions.
Professional bookkeeping also integrates well with tax reporting tools and tax professionals. If you need support preparing financial records or reports, the team at A.Y. Miller can help with accurate, timely bookkeeping, reporting, and tax prep. See How Do I Generate Tax Reports for My Accountant? Quick & Easy Guide for more on preparing organized records.
When records are well-maintained, it also reduces the risk of missed deductions or costly errors. Consistent recordkeeping helps with everything from quarterly estimated tax calculations to payroll filings and compliance reviews.
Planning Tips to Avoid Penalties
Meeting deadlines is easier with advance planning. Here are a few practical steps small business owners can take:
Create a Tax Calendar
List all key federal, state, and local tax dates and set reminders in your calendar. This prevents missed deadlines and unexpected penalties.
Automate Payments and Filings
Where possible, enroll in automatic payments or use tools that help you calculate and submit estimated taxes and payroll deposits on time.
Review Quarterly
At least once per quarter, review your income and expenses. This helps you adjust estimated payments and detect reporting issues early.
Get Professional Support
If tax compliance feels overwhelming, a tax professional or accountant can help you manage deadlines, deductions, and filing strategies. For more guidance on whether professional help is right for you.
Staying ahead of tax deadlines is an essential part of responsible small business management. Whether you are preparing quarterly estimated tax payments, filing returns, or submitting payroll and information returns, knowing the key dates for 2025 and 2026 helps you avoid penalties and manage cash flow more effectively. With organized financial records and thoughtful planning, you can face each filing season with confidence rather than stress.
For help with bookkeeping, reporting, and tax prep that supports your compliance and financial planning, A.Y. Miller is here to support your business needs.
