If you made money this year from freelancing, gig work, a side hustle, or a small business, the IRS does not wait until April to get paid.
It expects a cut four times a year, and the next estimated tax deadline is September 15 — a date that sneaks up on millions of self-employed Americans who assume they have until spring.
The penalty for missing it is not dramatic, but it is real.
The IRS charges interest on underpayments, currently running at 7% annually, compounded daily.
On a $5,000 shortfall, that is roughly $350 a year in extra money gone — cash you could have kept by simply sending in a payment on time.
Here is the trap: estimated taxes are not just for people with a 1099.
If you have a regular job but also drive for a rideshare app, rent out a room, or earn interest and dividends, you may owe too.
The rule of thumb is that you need to pay at least 90% of this year's tax bill or 100% of last year's, whichever is smaller, through withholding plus estimated payments.
Most people get hit with a surprise because they forget the self-employment tax.
That is 15.3% on top of regular income tax, covering Social Security and Medicare.
A freelancer earning $60,000 can owe thousands more than they expected, even after deductions.
The easiest fix is the IRS Direct Pay tool or your IRS online account, both free.
You can schedule a payment for September 15 right now so you do not forget.
If you are short on cash, pay what you can — partial payments reduce the penalty compared to skipping entirely.
One underused trick: if you have a W-2 job, you can ask your employer to withhold extra from your paycheck instead of making quarterly payments.
Withholding is treated as paid evenly throughout the year, which can wipe out penalties even if you catch up late.
If your income dropped this year or you have a big deduction coming, you can also use the annualized income installment method on Form 2210 to lower or skip a payment.
It is more paperwork, but it can save real money for people with lumpy income.
The bottom line is that the September deadline is not optional, and ignoring it compounds.
A 15-minute session with your IRS account or a tax pro this week is cheaper than the penalty you will pay in April.
Final Thoughts
Set a calendar reminder, make the payment, and keep the difference.