Your first year of gig income comes with a tax you never paid as an employee: self-employment tax, 15.3% of most of your profit, charged before income tax even starts. Nothing was withheld to cover it, so the IRS expects you to send it yourself, four times a year.
Where the 15.3% comes from
Every worker pays FICA taxes for Social Security and Medicare. On a W-2 job the bill is split: 7.65% comes out of your paycheck (6.2% Social Security plus 1.45% Medicare) and your employer pays a matching 7.65% you never see. When you're self-employed you are the employer too, so you owe both halves. That combined 15.3% is self-employment tax, figured on Schedule SE with your Form 1040.
| W-2 employee | Self-employed (you) | |
|---|---|---|
| Social Security | 6.2% employee share + 6.2% employer share | 12.4% |
| Medicare | 1.45% employee share + 1.45% employer share | 2.9% |
| Total | 7.65% out of your pay | 15.3%, on 92.35% of net profit |
| Owed from | Your first dollar of wages | $400 of net earnings in a year |
Three details make the real bite smaller than the headline:
- It applies to 92.35% of your net profit, not all of it. The 7.65% shaved off mirrors the employer half that isn't counted as an employee's wages. On $6,500 of profit, only $6,002.75 is taxed.
- The Social Security part stops at the wage base. Only the first $176,100 of your combined 2025 wages and net earnings is subject to the 12.4% part. The 2.9% Medicare part has no cap, and a 0.9% Additional Medicare Tax applies above $200,000 of income if you're single ($250,000 married filing jointly).
- Half of it is deductible. You deduct one-half of your self-employment tax as an adjustment to income (Schedule 1, line 15), which lowers the income your income tax is figured on. It doesn't reduce the 15.3% itself.
Self-employment tax sits on top of ordinary income tax. Your profit is taxed twice over: once at your marginal rate along with the rest of your income, and again at 15.3% for Social Security and Medicare. That stacking is why the 25% set-aside in getting paid as a gig worker covers both layers at once.
Why the IRS wants money four times a year
Federal tax is pay-as-you-go. A W-2 job satisfies that through withholding; a gig has nothing withheld, so once you expect to owe $1,000 or more for the year after withholding and credits, the IRS expects estimated taxes in four installments. Each covers income tax and self-employment tax together, and you figure them on Form 1040-ES.
| Payment | Covers income earned | Due (for 2026 income) |
|---|---|---|
| 1 | January 1 – March 31 | April 15, 2026 |
| 2 | April 1 – May 31 | June 15, 2026 |
| 3 | June 1 – August 31 | September 15, 2026 |
| 4 | September 1 – December 31 | January 15, 2027 |
The "quarters" are uneven (three months, two, three, then four), and a due date that lands on a weekend or holiday moves to the next business day. Pay online through your IRS Online Account or IRS Direct Pay, or mail the 1040-ES voucher. If you also have a W-2 job there's a simpler route: file a new W-4 and have your employer withhold extra from each paycheck, which the IRS counts exactly like estimated payments. The W-4 and your withholding shows where that line is.
Safe harbor and the underpayment penalty
Pay too little during the year and the IRS adds an underpayment penalty: an interest-style charge on each quarter's shortfall, figured on Form 2210. You owe no penalty if you meet any one of these tests:
| Safe-harbor test | What it means |
|---|---|
| You owe less than $1,000 after withholding and refundable credits | Small balances are penalty-free |
| Withholding plus estimates reach 90% of this year's tax | Track the real bill as the year goes |
| Withholding plus estimates reach 100% of last year's total tax | Use a number you already know |
| 110% of last year's tax instead, if last year's AGI was over $150,000 ($75,000 married filing separately) | The higher-income version of the same rule |
The 100%-of-last-year path is the friend of a new side hustle: match last year's total tax through withholding and estimates and no penalty applies, however much the gig grows this year. You still owe the balance in April, but without the extra charge. Refunds, balances, and not panicking covers what that balance looks like on the return.