09/11/2026
Business owners have plenty to keep track of. Here’s one date worth putting on your calendar: September 15, 2026. 📅
Two federal deadlines are approaching:
• Extended 2025 returns for calendar-year partnerships and S corporations with a valid extension.
• Third-quarter estimated tax payments for 2026, if required.
Missing the filing deadline can mean monthly penalties, even if the business owes no income tax. Paying estimated taxes late or paying too little may trigger an underpayment penalty.
If either applies to you, check in with your tax preparer this week. A quick conversation now can help prevent extra costs later.
Special deadline relief may apply.