If you get a paycheck with taxes already taken out, you can skip this one.
Everyone else—freelancers, gig drivers, small business owners, people earning money from investments or a side hustle—needs to pay attention to a date that sneaks up four times a year.
The IRS doesn't wait until April to get its money.
It expects estimated tax payments throughout the year, and the next due date is September 15.
Miss it and you can get hit with a penalty, even if you plan to pay everything you owe when you file your return in the spring.
Here's the part that catches people off guard: the penalty isn't a one-time slap on the wrist.
The IRS charges interest that compounds daily on the amount you should have paid.
Right now that interest rate sits around 7% to 8% for individuals, which is higher than what most savings accounts pay you.
In other words, holding onto that money "just in case" can cost more than it earns.
The rule of thumb is that if you expect to owe at least $1,000 when you file your return, you probably need to make quarterly payments.
That includes anyone who is self-employed, works as an independent contractor, earns significant income from dividends, rent, or a side gig, or had taxes withheld that won't cover the bill.
The math sounds intimidating, but it doesn't have to be.
A simple approach is to look at last year's total tax bill, divide it by four, and send that amount each quarter.
If your income changed a lot, you can use the IRS's worksheet or a free online calculator to get closer.
You don't need to be perfect—you just need to be in the ballpark to avoid the penalty.
There's also a safe harbor that a lot of people don't know about.
If you pay at least 90% of what you owe for the current year, or 100% of what you owed last year (110% if your income was above $150,000), the IRS won't charge you a penalty for underpayment.
That second option is a lifesaver for anyone whose income jumped unexpectedly.
Mark your calendar for the remaining dates this year: September 15 and January 15.
You can still send a payment now to stop the interest from growing.
The IRS also offers an online payment system where you can schedule a transfer directly from your bank account at no extra charge.
One more thing worth checking: if you also have a regular job with withholding, you can ask your employer to take out a little extra each paycheck.
That extra withholding counts toward your estimated tax obligation, and it's a painless way to avoid scrambling for a lump sum four times a year.
The bottom line is that the tax system rewards people who pay as they go and quietly penalizes those who wait.
Setting aside a percentage of every payment you receive—20% to 30% is a common starting point—keeps you from spending money that was never really yours.
Final Thoughts
A few minutes of planning now beats a surprise bill and a penalty later.