If you earn money that doesn't come with a W-2, the tax calendar doesn't wait until April.
The IRS expects payments four times a year, and the next installment lands on September 15 for most filers.
Miss it, and the penalty math starts ticking immediately, even if you're owed a refund when you finally file.
Freelancers, gig drivers, rideshare workers, small business owners, and anyone pulling income from investments or side hustles all fall into this bucket.
So do many retirees drawing from accounts without withholding.
Here's the part that trips people up: the IRS doesn't send a bill first.
It's on you to estimate what you'll owe and send it in.
By the time you get a notice, interest has already been stacking up.
It's calculated on the amount you underpaid, and it grows the longer you wait.
Right now that rate is steep enough to sting, especially if you owe thousands.
The IRS Direct Pay tool lets you send money straight from a bank account with no fee.
You can also schedule payments in advance, which is handy if you know a deadline is coming and don't want to think about it again.
If you'd rather pay with a card, expect a processing fee of roughly 1.85% to 2% depending on the processor.
On a $3,000 payment, that's real money, so a bank transfer usually wins.
If you pay at least 90% of this year's tax bill or 100% of last year's, whichever is smaller, you generally avoid the underpayment penalty.
Higher earners may need 110% of last year's figure instead.
That's the trick a lot of people use: just match last year's total and stop doing mental math.
It's not perfect, but it keeps the penalty off your back.
One more thing worth checking — if your income is uneven, the IRS allows an annualized method that can lower what you owe for slow quarters.
It takes more paperwork, but it can save money for people whose earnings spike and dip.
Set a phone reminder for September 15 and again for January 15.
Those two dates catch most people off guard because they don't line up with the April filing deadline everyone knows.
If cash is tight right now, send what you can rather than nothing.
Partial payments reduce the balance the penalty is calculated on, and the IRS will happily set up an installment plan online if you need more time.
Our take: the estimated tax system punishes people for not knowing the rules, not for breaking them.
Final Thoughts
A ten-minute payment today beats a letter from the IRS in March, so put it on your calendar before the week gets away from you.