If you're self-employed, there's a due date most people never put on the calendar, and it's already close.
The third-quarter estimated tax payment for 2025 lands on September 15, and it applies to freelancers, gig workers, independent contractors, small business owners, and anyone pulling income that doesn't have taxes withheld up front.
Miss it, and the IRS doesn't send a warning first.
It just adds a penalty on top of what you already owe.
Here's the part that catches people off guard: the IRS runs a pay-as-you-go system.
If you earn money without an employer withholding taxes, you're expected to send a chunk to the government four times a year, not once in April.
The remaining deadlines this year are September 15 and January 15, 2026.
The tricky math is that many workers don't know how much to send.
A common shortcut is to look at last year's total tax bill, divide it by four, and pay that amount each quarter.
If your income jumped this year, that approach can leave you short and exposed to an underpayment penalty.
A safer method is to set aside roughly 25 to 30 percent of each payment you receive for taxes, then send it in quarterly.
That covers federal income tax plus the 15.3 percent self-employment tax that gig and freelance workers owe on top of regular income tax.
There's also a rule worth knowing: if you owe less than $1,000 for the year, or you paid at least 90 percent of this year's tax or 100 percent of last year's, you can usually sidestep the penalty.
Higher earners may need to hit 110 percent of last year's bill instead.
Freelancers aren't the only ones affected.
Retirees drawing from investments, people with side hustles, and anyone who received a big one-time payment without withholding can all owe.
So can workers who took a distribution from a retirement account.
The easiest way to avoid a surprise is to make a free IRS account online and pay directly through IRS Direct Pay, which pulls straight from a bank account with no fee.
Credit card payments are accepted too, but the processors charge a convenience fee of roughly 2 to 2.5 percent, which can sting on a large bill.
If cash is tight, the IRS offers payment plans, and penalties can sometimes be reduced if you have a reasonable excuse.
But interest keeps running, so waiting rarely helps.
One more thing worth checking: if you had a job earlier in the year and then went freelance, your employer may have already withheld enough to cover part of your obligation.
Running the numbers before you pay could save you from overpaying.
The bottom line is that September 15 isn't a random date on the calendar for millions of independent workers.
Our take: estimated taxes are one of the most ignored parts of self-employment, and the penalty is avoidable with a little planning.
Set aside a percentage of every payment, pay through the free IRS portal, and mark the January date now.
Final Thoughts
A few minutes today beats a surprise charge later.