Understanding March 15 Tax Deadlines and Extensions

Every year, March 15 marks an important date on the tax calendar—especially for businesses structured as partnerships or S corporations. Staying ahead of this deadline can help you avoid penalties, plan effectively, and keep your filings running smoothly. Below is a helpful overview of what’s due, who it applies to, and how extensions work if you need a little extra time.

Who Must File by March 15?

The March 15 tax deadline applies primarily to:

• S Corporations filing Form 1120-S
• Partnerships filing Form 1065

These returns report the entity’s income, deductions, and other financial details. After filing, the entity issues Schedule K-1 forms to each shareholder or partner so they can report their share of business income on their personal returns.

Why This Deadline Matters

For pass-through entities, the March 15 deadline is designed to give partners and shareholders enough time to complete their individual tax returns by the April filing deadline. Missing the deadline can result in penalties, and delays can create ripple effects for everyone waiting on their K-1s.

Filing Extensions: What You Need to Know

If your books aren’t final or you’re waiting on important documents, filing an extension may be your best option. As noted in similar discussions of tax extensions in our resources, an extension simply gives you more time to file your return—it does not extend the time to pay any taxes owed.

Here’s how extensions work for March 15 filers:

• S Corporations can request a six-month extension using Form 7004, moving the due date to September 15.
• Partnerships can also request a six-month extension using Form 7004, with the same extended deadline of September 15.

Important Reminder About Payments

While an extension grants additional time to complete your return, any taxes owed by the entity (when applicable) or owners must still be paid by the original March 15 deadline to avoid penalties and interest. This aligns with the broader IRS rule that extensions never extend the time to pay.

Tips to Prepare Ahead of the Deadline

• Start gathering financial records early—including bank statements, payroll reports, and expense documents.
• Communicate with your tax professional about any complexities or missing pieces.
• Don’t wait until K-1s are finalized to begin individual tax planning.

Need Support?

March 15 can sneak up quickly, but you don’t have to navigate it alone. Whether you’re unsure about your filing requirements, need help preparing your return, or want guidance on whether to file an extension, Moss & Yantis CPA PA is here to support you through every step of tax season.

Reach out anytime—we’re here to help you stay organized, informed, and confident as you approach this key deadline.