Ready for Financial Confidence?
If you make quarterly estimated tax payments, the next big date on your calendar is September 15, 2025. This is the third quarterly tax deadline for the year, and it’s one of the most important because it covers income you’ve earned during the summer, a period that can bring unpredictable swings in cash flow for many businesses.
Missing this payment or paying the wrong amount can lead to penalties, interest, and a big tax bill in April. That’s why it’s important for you to know the specifics.
Who Needs to Pay Quarterly Taxes
The IRS requires estimated tax payments if you expect to owe at least $1,000 in tax for the year after subtracting withholding and credits. This applies to:
- Self-employed business owners
- Contractors and subcontractors
- Real estate professionals and investors with rental income
- S-corp owners who take distributions in addition to their salary
- Partners in a partnership or members in an LLC taxed as a partnership
- High-income W-2 earners with significant side income not covered by withholding
What the Third Quarterly Payment Covers
The third quarterly payment covers income earned June 1 through August 31, 2025 for most taxpayers using the regular quarterly schedule.
If your income is consistent, the IRS expects each payment to be roughly 25% of your total estimated tax bill for the year. But suppose your income is seasonal or unpredictable (i.e., many contractors and real estate investors). In that case, you may need to use the annualized income method to avoid overpaying in slow months or underpaying during busy ones.
How to Calculate Your Payment Accurately
Overpaying ties up cash you could use in your business. Underpaying triggers IRS penalties. Here’s how to get it right:
- Start with year-to-date income – Include all business, rental, investment, and other taxable earnings.
- Account for deductions – Expenses such as mileage, business equipment, insurance, and depreciation can significantly lower taxable income.
- Factor in tax credits – Energy credits, child tax credits, and other incentives can reduce your bill.
- Adjust for previous payments – Subtract what you’ve already paid in the first and second quarters.
- Use the correct tax rates – Federal rates plus state income tax if you are in a state that taxes income.
For clients with fluctuating income, we often run a mid-year projection in August. This ensures September’s payment is dialed in and avoids unnecessary penalties.
We run mid-year projections for clients in August so their September payment is spot on. If you want that kind of precision, let’s talk before the deadline.
How to Pay the IRS
The fastest and most secure method is through the IRS Direct Pay system for individuals or the Electronic Federal Tax Payment System (EFTPS) for businesses.
Other options include:
- Mailing a check with a Form 1040-ES payment voucher
- Same-day wire through your bank (fees may apply)
- Paying with a debit or credit card (third-party processing fees apply)
Exclusive Insight: Why September Matters More Than April
Many business owners think April is the only quarterly tax deadline that matters, but September is a strategic point in the tax year. By this date:
- You have a clear picture of your business performance for three-quarters of the year.
- You still have time to make tax-saving moves before December 31, such as buying equipment, adjusting payroll, or contributing to retirement plans.
- You can correct the course if you’ve been overpaying or underpaying in earlier quarters.
In other words, this is your last big checkpoint before year-end planning kicks in. You may also use the quarterly estimated tax checklist.
State Deadlines to Watch
While most states match the federal September 15 due date, a few have different schedules or additional forms. If you operate in Louisiana, Texas, Alabama, Mississippi, Florida, or Tennessee, the rules are generally aligned with the IRS. However, Tennessee’s Hall Income Tax on certain investment income and Florida’s lack of state income tax mean planning still matters for other obligations, like sales tax or local business taxes.
If you want expert help with tax preparation and filing, contact us.
FAQ
What exactly does the third quarterly tax deadline 2025 cover?
It covers income earned June 1–August 31. Payment must hit the IRS by September 15, 2025.
When are Q3 estimated taxes due?
The third quarter taxes are due September 15, 2025.
I earned income midyear. Do I really owe four equal payments?
Not always. If you’re new to estimated taxes, your first payment might land on September 15 rather than April. You’re expected to pay 75% of the estimated yearly tax, not 25%, if income started mid-year. File Form 2210 to explain that timeline and avoid penalties.
Are there safe-harbor rules to avoid penalties on estimated taxes?
Yes. Pay either 100% of last year’s tax (110% for high-income) or 90% of this year’s liability, whichever is lower.
Can paying later in the month or on a weekend slip past as on-time?
Yes. If September 15 falls on a weekend or holiday, your payment counts as timely if made the next business day. The IRS automatically adjusts for that.
Can I pay estimated tax at any time, not just quarterly?
Absolutely. You can pre-pay anytime. The key is that by September 15 you must have “timely” covered either the safe-harbor amount or 90% of current year’s liability.
How much should I pay if I sold a bunch of stock in February?
Stick to the standard schedule. You can still pay quarterly. Even if you had big gains early in the year, the IRS expects payment following the normal due dates.
I just started making money, am I required to pay estimated tax in 2025?
If you didn’t owe tax in 2024, you may not need to pay quarterly in 2025 right away. But once your income rises and you expect to owe $1,000+, the obligation kicks in. The safe harbor relies on 2024 liability.
What are the exact deadlines for quarterly estimated tax payments in 2025?
They are:
• April 15, 2025 (Q1: Jan–Mar)
• June 16, 2025 (Q2: Apr–May; pushed due to weekend)
• September 15, 2025 (Q3: Jun–Aug)
• January 15, 2026 (Q4: Sep–Dec)
