If you made money on the side this year and didn't send anything to the IRS, you may be in for a nasty surprise.
The third-quarter estimated tax deadline landed on September 15, and it's catching a lot of people off guard.
Estimated taxes aren't just for the self-employed.
Anyone with income that doesn't have taxes automatically withheld — gig work, freelancing, a side hustle, rental income, or even a big investment payout — is supposed to pay as they go, four times a year.
The rule most people miss: you generally owe a penalty if you don't pay enough tax throughout the year, even if you get a refund when you file.
The IRS charges interest on that shortfall, and it adds up quietly month after month.
If you expect to owe at least $1,000 when you file your return, the IRS wants you making quarterly payments.
That threshold is lower than most people assume.
The good news is there's a simple fix if you already have a regular job.
You can ask your employer to withhold extra from each paycheck by updating your W-4.
That keeps you covered without remembering four separate deadlines.
If you're fully self-employed, the math is murkier.
You owe income tax plus self-employment tax, which covers Social Security and Medicare.
A common shortcut is to set aside 25 to 30 percent of every payment you receive into a separate savings account.
Send a payment now through IRS Direct Pay or your IRS online account.
The penalty grows the longer you wait, so paying late beats not paying at all.
If your income jumped this year — a raise, a new client, a one-time bonus — you may owe more than last year even if you paid the same amount.
The safe harbor rules protect you if you paid at least 100 percent of last year's tax, but that only works if you actually hit that number.
The next deadline is January 15 for the fourth quarter.
That's also a smart time to do a rough calculation for the whole year so April doesn't blindside you.
One low-effort move that pays off: open a separate savings account just for taxes and move a set percentage there every time money comes in.
You won't earn much interest, but you won't be scrambling either.
This is one of those boring financial chores that quietly punishes people who ignore it.
A few minutes with a calculator now can save you hundreds in penalties later.
Final Thoughts
If your situation is complicated, a one-time session with a tax pro often costs less than the fee the IRS would charge you.