For many US small businesses, September means more than just the end of summer—it’s also time to prepare for the third-quarter estimated tax payment. The deadline this year is September 16, 2025 (moved from the usual September 15 because it falls on a weekend). This deadline applies to income earned between June 1 and August 31, 2025.
Whether you manage your books in-house or work with accounting services in the US, staying ahead of this deadline helps avoid penalties and keeps your business compliant.
Small business owners—including sole proprietors, freelancers, S corporations, and partnerships—must calculate and submit their Q3 estimated taxes using Form 1040-ES or the appropriate form for their entity type. Payments can be submitted through:
If your state imposes income tax, you may also need to file a separate estimated tax payment. Check with your state’s Department of Revenue for deadlines and forms.
Ensure your books are current. Accurate financial data is essential for calculating how much tax you owe. Accounting services that use smart automation tools can help update and reconcile records faster and more accurately.
If your income changed significantly this quarter, consider adjusting your withholdings or estimated payments. This prevents overpaying or underpaying your taxes and reduces your risk of year-end surprises.
Prepare and organize the following:
This documentation helps both with payment accuracy and audit readiness.
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Missing a quarterly tax payment can result in:
Even if you expect a refund at year-end, penalties may apply if quarterly payments are insufficient. It’s always safer to pay as you go.
Small business owners often benefit from working with accounting professionals who use automation tools like Smart Rules to:
Accounting services bring accuracy and consistency to your financial management, especially around deadlines like September 16.
If you’re a US small business owner, the September 16, 2025 estimated tax payment deadline is one you can’t afford to miss. Prepare by reviewing your Q3 earnings, updating your records, and submitting payments using Form 1040-ES or state equivalents. Consider working with a professional accounting service that uses smart automation to improve accuracy and ease the process. Staying proactive with your taxes means fewer penalties and a smoother year-end filing.
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