If you earn money that doesn't come with an employer withholding taxes, the calendar is about to tap you on the shoulder.
The next estimated tax payment for most filers lands on September 15, and it covers income you made from June through August.
Miss it, and the IRS can tack on a penalty that compounds daily — even if you're owed a refund come spring.
That surprises a lot of people who assume a refund erases the problem.
Freelancers, gig drivers, consultants, small-business owners, and landlords top the list.
But there's a quieter group that gets caught off guard every year: retirees pulling from 401(k)s and IRAs, plus anyone earning serious interest or dividends.
If you expect to owe at least $1,000 when you file, the IRS generally wants money throughout the year, not in one lump in April.
You can pay online in minutes through IRS Direct Pay or your IRS online account, and there's no fee for a bank transfer.
A safe approach is to match what you owed last year, or hit 90% of what you'll owe this year.
If your income jumped, the second number matters more.
If it dropped, you may be able to skip a payment entirely.
A common and expensive mistake is forgetting that self-employment tax exists.
That's 15.3% on top of regular income tax, covering Social Security and Medicare.
Freelancers who only set aside for income tax get blindsided by a bill that's roughly a third bigger than they planned.
If you paid at least as much as your prior year's total tax — and your adjusted gross income was under $150,000 — you're usually protected from the underpayment penalty, even if you write a big check in April.
Higher earners need to cover 110% of last year's bill.
Skipping a payment can also trigger a penalty on top of a penalty.
The IRS charges interest on unpaid balances, and rates have stayed elevated compared with the rock-bottom years of the early 2020s.
That's real money leaking out for no reason.
Log into your IRS online account, check what you've already paid this year, and send the difference before the 15th.
If cash is tight, send something rather than nothing — partial payments reduce the penalty.
One more thing worth doing now: nudge your withholding.
Employees can submit an updated W-4, and retirees can adjust withholding on pension and Social Security payments.
Fixing it at the source beats scrambling four times a year.
My take: estimated taxes are boring, which is exactly why so many people ignore them until a letter shows up.
Ten minutes on the IRS website this week is cheaper than a penalty that quietly follows you into next filing season.
Final Thoughts
Set a phone reminder for the January deadline while you're at it.