As a business owner, staying on top of your tax deadlines is crucial for maintaining compliance with the IRS and avoiding penalties. Missing or incorrectly filing a return can lead to costly fines, interest charges, and unnecessary stress. Whether you’re running a partnership, an S corporation, a C corporation, or a single-member LLC, knowing your specific tax deadlines is key to smooth financial operations.
In this article, we’ll walk you through the most important 2025 business tax deadlines and provide helpful tips for staying organized and filing on time.
Partnership tax return deadline 2025 (Form 1065): March 15
If your business operates as a partnership, you must file Form 1065, “U.S. Return of Partnership Income,” by March 15 every year. A partnership is an arrangement where two or more individuals (or entities) share ownership and management of a business, and profits or losses are passed through to the partners’ individual tax returns.
It’s important to note that you cannot miss this deadline without facing penalties. If you fail to file on time, the IRS will charge penalties based on the number of partners and the length of time the return is late.
What happens if you file late?
The IRS charges penalties based on the number of partners and the length of delay. In 2025, the penalty is $220 per partner, per month, up to 12 months.
Extension for partnerships
If you need more time to file your partnership tax return, you can request an extension. However, this extension must be filed before the March 15 deadline. If you don’t file the extension on or before the deadline, you risk facing penalties, even if the form is filed later. Extensions typically provide an additional six months to file, pushing the final deadline to September 15.
S Corporation tax return deadline: March 15
An S corporation, which is a special type of corporation that avoids double taxation by passing income, deductions, and credits through to its shareholders, shares the same deadline as a partnership. You must file the Form 1120S (S Corporation Income Tax Return) by March 15 every year.
Extension for S Corporations
As with partnerships, S corporations can file for an extension before the March 15 deadline to gain an additional six months – making the final deadline September 15. However, it’s essential to note that the extension only grants extra time to file the paperwork. Any taxes owed must still be paid by the original March 15 deadline to avoid penalties and interest.
C Corporation tax return deadline: varies based on fiscal year
C corporations, which are separate legal entities taxed independently from their owners, have a different deadline structure depending on their fiscal year.
- If your fiscal year ends December 31: Your Form 1120 is due April 15, 2025.
- If you have a non-calendar fiscal year: Your deadline is the 15th day of the fourth month after your fiscal year ends (e.g., a June 30 year-end means a deadline of October 15).
Extension for C Corporations
Just like S corporations and partnerships, C corporations can file for an extension. However, the same rule applies: you must file for the extension on or before the original deadline. For example, if your fiscal year ends on June 30, you must file for an extension by October 15 if you need more time.
Single-Member LLCs tax return deadline: April 15
A single-member LLC is considered a disregarded entity for tax purposes, meaning the LLC itself does not file a separate tax return. Instead, the income or loss from the LLC is reported on the owner’s personal tax return. Therefore, the tax deadline for a single-member LLC is tied to your individual income tax return, which is typically due on April 15.
Since the LLC is disregarded, you will report your LLC income, deductions, and expenses on Schedule C of your personal tax return (Form 1040). If you need more time to file, you can request an extension to file your personal tax return, which would push the deadline to October 15.
Important notes about extensions
For all business entities, it’s essential to remember that while extensions give you more time to file your tax return, they do not extend the time to pay any taxes owed. You’re still expected to make an estimated payment by the original deadline. Failing to do so can result in:
- Late payment penalties
- Accrued interest on the unpaid balance
- Potential loss of good standing with the IRS
Pro tip: Use IRS Direct Pay or EFTPS to make timely estimated payments.
Estimated tax payments
Most pass‑through entities and C‑corps must make quarterly estimates. Missing these can trigger underpayment penalties. The following are important estimated tax payment dates for business owners. You can work with us at Waldman Accounting to determine what you need to pay and when to avoid penalties.
- Q1: April 15
- Q2: June 15
- Q3: September 15
- Q4: January 15 (following year)
Pro tip: Use IRS Direct Pay or EFTPS to make timely estimated payments.
How to stay organized and avoid missing deadlines
- Create a Tax Calendar – Mark key tax deadlines for each of your business entities on your calendar well in advance. Setting reminders will help keep you on track.
- Consult Your Accountant Early – It’s a good idea to meet with your accountant or tax advisor early in the year to plan for any anticipated tax liabilities and discuss potential strategies to minimize them.
- File Extensions on Time – If you think you may not be ready to file on time, make sure to file for an extension before the deadline. Missing the extension deadline can result in penalties.
- Keep Detailed Records – Keep accurate records of your business income and expenses throughout the year. This will make tax filing smoother and ensure you don’t miss any deductions or credits.
Conclusion
Staying on top of your tax deadlines is one of the best ways to ensure your business avoids penalties and remains compliant with the IRS. Whether you’re filing as a partnership, S corporation, C corporation, or single-member LLC, understanding your tax deadlines and filing on time is essential. If you need more time, don’t forget to file an extension—but make sure you do it on time. With proper planning, you can confidently navigate tax season without unnecessary stress.
If you’re unsure about which forms apply to your business or need help filing your tax returns, reach out to us at Waldman Accounting. We will guide you through the process and ensure your business stays on track.