Missed the Q2 Estimated Tax Deadline? Here’s What to Do Right Now

June 15 came and went. If you missed the Q2 estimated tax deadline — or made a payment that was smaller than it should have been — take a breath. You’re not the first, and this is fixable.

Here’s what you actually need to know.

What Happens When You Miss a Quarterly Payment?

The IRS charges an underpayment penalty based on the current federal short-term interest rate plus 3 percentage points. As of 2026, that’s roughly 7–8% annualized — applied to the amount you should have paid, for the number of days it was late. It’s not catastrophic for one missed quarter, but it adds up across four.

The good news: missing one deadline doesn’t mean you owe it all right now. You can make up the difference in your Q3 payment (due September 15), and a tax professional can help you calculate the most efficient path to minimize the penalty.

Don’t Forget Illinois — Most People Do

This is the one that catches Chicago-area business owners off guard. Illinois has its own separate estimated tax system through the Illinois Department of Revenue (IDOR) at mytax.illinois.gov. It mirrors the federal schedule but it’s a completely separate payment to a separate agency.

If you only paid the IRS and skipped IDOR, you may be accumulating state penalties right now without realizing it. Illinois taxes pass-through income at a flat 4.95% — that’s real money if you’ve been ignoring it all year.

Who Has to Pay Estimated Taxes?

• Sole proprietors and freelancers
• Single-member and multi-member LLCs
• S-corp owners taking distributions
• Anyone who expects to owe at least $1,000 in federal taxes and doesn’t have enough withholding to cover it

Your Next Steps

• Calculate what you should have paid for Q2 using either the safe harbor method (100% of last year’s tax, or 110% if your prior-year AGI was over $150,000) or your actual Q1–Q2 income
• Make an IRS payment at irs.gov/payments — free, no account required
• Make a separate Illinois payment at mytax.illinois.gov
• Put September 15 on your calendar right now for Q3

The worst thing you can do is nothing. Every additional day increases the penalty exposure. A small catch-up payment now is always better than a larger problem in January.

At JIL & Associates, we specialize in tax planning and quarterly estimated tax calculations for small business owners across the Chicago area. We’ll help you figure out exactly what you owe and get back on track before Q3. 📞 Call (630) 828-3648 or schedule a free consultation today!