April 15 just passed. You filed, you paid, you exhaled. And now, if you’re like most small business owners, you’ve mentally closed the tax chapter until fall.
Not so fast.
June 15 is your next estimated tax deadline and it has a quirk that catches business owners off guard every single year. Understanding it now, while you still have time to prepare, is one of the most financially smart things you can do this month.
The Estimated Tax System, Explained Simply
If you’re self-employed, an S-Corp owner, a partner in a business, or anyone whose income isn’t subject to automatic withholding, the IRS expects you to pay your taxes as you earn, not just once a year in April. This is the estimated tax system.
The IRS breaks the year into four payment periods, each with its own deadline. Miss a deadline or underpay, and you’ll face an underpayment penalty even if you write a check for the full balance when you file your return. The penalty isn’t enormous, but it’s entirely avoidable, and that’s the point.
For 2026, the federal estimated tax deadlines are April 15, June 15, September 15, and January 15, 2027.
The Q2 Problem Nobody Warns You About
Here’s what makes Q2 different from every other quarter: it’s short.
Q1 covers January through March… three full months. Q3 covers June through August. Q4 covers September through December. But Q2? It covers only April and May. Two months instead of three, and the deadline still hits June 15.
That compressed timeline is exactly why Q2 catches so many business owners flat-footed. You’re mentally thinking in quarters — equal parts, evenly spaced. But the IRS is not thinking that way, and your cash flow plan shouldn’t be either.
Q2 covers only April and May. If you’re budgeting as if all four quarters are equal, your Q2 estimate is probably off.
For businesses with seasonal revenue, project-based income, or any kind of cash flow variability, this matters even more. The amount you owe isn’t based on how much you made in a tidy three-month window. It’s based on your cumulative income, your prior year liability, and which safe harbor method you’re using.
Two Ways to Calculate What You Owe
There are two common approaches to calculating quarterly estimated payments, and the right one depends on your business.
The first is the prior year safe harbor. You pay 100% of what you owed in federal income tax last year (or 110% if your prior year adjusted gross income exceeded $150,000), divided into four payments. This method is simple and protects you from penalties even if your income jumps significantly, but it can result in overpaying or underpaying relative to what you actually earned.
The second is the current year method. You estimate what you’ll actually owe this year based on year-to-date income, project it forward, and pay accordingly. This is more accurate, but it requires current, reliable financial data. If your books are behind or disorganized, this method becomes a guessing game and guessing with estimated taxes is how people end up with penalties.
Most tax professionals will recommend a combination of both approaches, calibrated to your specific situation. That conversation is worth having before June 15, not after.
What You Should Be Doing Right Now
Pull your year-to-date numbers. You need to know where you stand through April and May before you can make an informed payment. If your books are current, this takes minutes. If they’re not, this is the moment you realize what that gap is costing you.
Compare to last year. What did you owe? What have you paid so far? Is your income tracking higher, lower, or about the same? This comparison gives you a working baseline even if your current year projection isn’t fully built out.
Talk to your CPA before June 1. They need time to run the numbers. Calling the week of June 15 limits what they can do for you and it limits your options.
Set the cash aside now. Estimated taxes are not a surprise expense when you plan for them. The goal is to have the money sitting in a separate account, untouched, before the deadline arrives. If you’re not doing this yet, start with Q2.
The Books Behind the Math
Here’s the through-line in all of this: every good estimated tax decision depends on accurate, current financial data. Your CPA can only give you a solid projection if they have clean numbers to work with. Your payment can only be calibrated correctly if you know what your income and expenses actually look like.
This is where bookkeeping stops being administrative and starts being strategic. When your books are closed monthly — not quarterly, not annually, monthly — you always know where you stand. Q2 doesn’t sneak up on you. June 15 doesn’t create a cash flow crisis. You make a decision based on real numbers and move on.
At TEVA, we keep books current so that moments like this are decisions, not emergencies. If you’ve been thinking about getting your financials in better shape before the next deadline, this is a good time to start that conversation.
The Bottom Line
Q2 estimated taxes are due June 15. The quarter is shorter than you think, the deadline is closer than it feels, and the calculation requires data you may not have organized yet.
File on time. Pay what you actually owe. And get your books in order so that the next one doesn’t catch you off guard either.