There’s something timely in the air, and no, we’re not talking about pumpkin spice—it’s fall tax deadlines. While many associate April with taxes, the fall months come with their own set of important deadlines that individuals and businesses can’t afford to overlook. Missing these deadlines can lead to penalties, interest, or missed opportunities for savings. Our team has put together this quick overview of what you need to know to stay compliant and ahead of the curve.
Key Fall Tax Deadlines To Remember
September 15, 2025: Third quarter estimated tax payments due (individuals and businesses)
If you’re self-employed or have income not subject to withholding (like rental income or dividends), you’re likely required to make quarterly estimated tax payments. The third installment for the 2025 tax year is due Tuesday, September 16. This applies to:
- Sole proprietors
- Partners
- S corporation shareholders
- Freelancers and gig workers
Businesses that pay quarterly taxes should also mark this date. Paying on time helps you avoid underpayment penalties when filing your annual return.
October 15, 2025: Extended corporate tax returns (calendar-year C corporations)
If your C corporation filed for an extension back in April, your extended tax return is due on this same date. This includes:
- Filing your Form 1120
- Making any final tax payments owed for the 2024 tax year
This is also a good time for year-end tax planning. If your business is experiencing significant changes in income, expenses, or structure, reach out to us before the end of Q3.
October 15, 2025: Extended individual tax returns
Did you request a six-month extension for filing your Form 1040 last April? Your extended deadline is coming up in mid-October. Important reminders for extended filers:
- This is a filing deadline only; any taxes owed were still due in April.
- Double-check for updated documents or corrected tax forms (like a revised 1099).
- Make sure to file electronically to speed up processing and reduce errors.
- If you’re working with our team, please get your documentation to us well before October to avoid last-minute issues.
October 15, 2025: Extended SEP IRA and Solo 401(k) contributions
If you’re self-employed and filed for an extension, October 15 is also the last day to fund a SEP IRA or Solo 401(k) for the 2024 tax year. These retirement plans offer excellent tax-deferral opportunities:
- SEP IRAs allow contributions of up to 25% of compensation (with a 2024 cap of $69,000).
- Solo 401(k)s may allow both employee and employer contributions if the plan was established before the end of the tax year.
Why These Deadlines Matter
Failing to meet fall deadlines can bite you in the wallet in more ways than one:
- Late filing penalties, which increase the longer you wait
- Interest charges on any unpaid taxes
- Missed tax benefits, such as retirement plan deductions or carryover credits
For businesses, especially, timely filing is crucial for cash flow planning, loan applications, and maintaining good standing with investors or partners.
How To Stay on Track
Here are a few strategies to help you stay organized:
- Set calendar reminders a few weeks ahead of each deadline.
- Keep financial documents organized throughout the year to avoid a scramble in September or October.
- Use accounting software that integrates with your tax preparation tools to streamline reporting.
- Consult with our team mid-year to review your tax position and adjust estimated payments if needed.
Déjà Vu All Over Again
Yes, it seems like we just went through all this a few short months ago, doesn’t it? Fall may not feel like “tax season,” but these months are just as important for staying in compliance and making smart financial moves. Whether you’re filing an extended return, making estimated payments, or contributing to a retirement plan, the key is to prepare early and stay informed.
If you have questions about your filing obligations or want to discuss proactive tax strategies for the rest of the year, don’t hesitate to reach out. Our team is here to help you navigate the fall deadlines with confidence and clarity.