Have a W-2 job and a side gig? Get your extra withholding in 60 seconds.
Open the free calculator →The short answer
- W-2 job plus side income: add the tax on the side income to Step 4(c) of your W-4, so your employer withholds it from each paycheck.
- 1099 income only: a W-4 doesn't apply. Pay quarterly estimated taxes (2026 dates below).
- Self-employment tax (15.3% on 92.35% of net profit, about 14.13%) is on top of income tax. Plan for both.
- Rule of thumb: set aside roughly 25–35% of net freelance profit. The exact figure depends on your bracket. Use the worked examples below.
Which situation are you in?
W-2 job + side gig
Use your W-4Your employer already withholds on your wages, so raise that withholding to cover the side income too. This guide's main method (Step 4(c)) is built for you.
1099 / self-employed only
Pay quarterlyNo employer, no W-4. You send the IRS both taxes yourself through quarterly estimated payments (Form 1040-ES). See the estimated tax section and the 1099-only example.
Irregular side income
Either worksA big quarter, then nothing? A fixed W-4 amount over- or under-pays. Quarterly payments track actual profit, or you can revisit your W-4 whenever your income changes (you can submit a new one any time).
The problem: side income has no withholding
When you work a W-2 job, your employer withholds federal income tax, Social Security, and Medicare from every paycheck. When you freelance or drive for a gig app, no one does that for you. Every dollar of self-employment income arrives gross, and you owe taxes on it.
Most people discover this in April, when a $15,000 side gig turns into a bill of several thousand dollars they hadn't budgeted for. The fix is to prepay the tax during the year, either through extra withholding at your day job or through quarterly estimated payments.
Two taxes on self-employment income
Federal income tax
Ordinary ratesYour net freelance profit is added to your other income, taxed at your marginal rate and possibly pushing part of it into a higher bracket.
Self-employment (SE) tax: 15.3%
Not in a W-4 by defaultThe self-employed pay both halves of Social Security (12.4%) and Medicare (2.9%). It applies to 92.35% of net earnings when those are $400 or more (Schedule SE). Half of the SE tax is then deductible when you figure income tax.
Two limits worth knowing: the 12.4% Social Security part stops at the annual wage base ($184,500 for 2026, counting your W-2 wages too), and an extra 0.9% Medicare tax applies to high earners (above $200,000 for a single filer). Most side-gig earners are far below those levels. For the definition, see our self-employment tax glossary entry.
How to set your W-4 when you have a W-2 job and side income
The IRS says that if you want self-employment taxes paid through your wages, you should use its Tax Withholding Estimator to work out the amount. That's the most accurate route because it sees your whole picture. If you'd rather do it by hand, this is the simple method. It estimates the extra tax and puts it all in Step 4(c):
Estimate your net freelance profit for the year: income minus business expenses. Be conservative, and it's better to over-withhold slightly.
Self-employment tax = net profit × 0.9235 × 0.153. Then take half of it as your deduction.
Income tax on the side income = (net profit − half the SE tax) × your marginal rate. Add it on top of your wages' taxable income, so if it crosses a bracket edge, split it across the two rates.
Add the SE tax and the income tax, divide by your remaining pay periods, and enter that amount in Step 4(c) of a new W-4 for your employer.
Recheck when your side income changes, and again in December. You can submit a new W-4 at any time.
Step 4(c) or Step 4(a)? Both work, but only one covers self-employment tax
On the form, Step 4(a) is for "other income (not from jobs)", and its examples are interest, dividends and retirement income. Step 4(a) raises income tax only, so it never covers self-employment tax. Working out one dollar figure and entering it in 4(c) covers both taxes in a single line. Our W-4 calculator uses the other route: your side income goes in 4(a), and the self-employment tax goes in 4(c). The next section shows both.
Two ways to fill in the W-4 for the same $15,000 side gig
| Method A: all in 4(c) | Method B: 4(a) plus 4(c) | |
|---|---|---|
| Step 4(a) | $0 | $15,000 |
| Step 4(c), biweekly | about $174 | about $82 (self-employment tax only) |
| Income tax part | You work it out by hand | Your employer's payroll tables do it (about $102 per paycheck) |
| Total extra per paycheck | about $174 | about $184 |
$60,000 salary, single, 26 paychecks. Method B is a little higher because 4(a) treats the full $15,000 as taxable and ignores the half-of-self-employment-tax deduction, so it errs toward a small refund.
The mistake to avoid is doing half of Method B: writing the side income in 4(a) and stopping there. Your paycheck withholding goes up, so it looks handled, but the self-employment tax (about $2,119 on $15,000) is still unpaid and shows up as a bill in April. Whichever method you pick, make sure the 15.3% tax is covered somewhere, in 4(c) or in quarterly estimates.
Worked example: $60,000 job plus $15,000 side gig (single)
📊 Filing single, 2026 federal brackets, no other adjustments
Wages: $60,000, so taxable income before the side gig = $60,000 − $16,100 standard deduction = $43,900 (12% bracket, which ends at $50,400)
SE tax: $15,000 × 0.9235 × 0.153 = $2,119
Deduction: half of SE tax = $1,060, so extra taxable income = $15,000 − $1,060 = $13,940
Income tax: $6,500 at 12% ($780) + $7,440 at 22% ($1,637) = $2,417
Total extra tax: $2,119 + $2,417 = $4,536 (about 30% of the $15,000)
Per biweekly paycheck: $4,536 ÷ 26 = about $174 in Step 4(c)
Simplified estimate: it leaves out state tax and credits, and it ignores the qualified business income deduction, which some freelancers can claim and which would lower the bill. If you start mid-year, divide by the remaining pay periods, not 26.
Calculate your W-4 with side income — free
Enter your W-2 pay and your freelance earnings to see the extra amount to withhold each paycheck.
Open the W-4 Calculator →Estimated taxes: who has to pay them, and when
Estimated tax is how income with no withholding gets paid during the year. The IRS says you generally must make estimated payments if you expect to owe $1,000 or more after subtracting withholding and credits. If you have a W-2 job, extra withholding can cover that instead, and the IRS treats withholding as paid evenly through the year (see Publication 505).
| Payment | Covers | Due (2026) |
|---|---|---|
| 1st | Jan 1 – Mar 31 | April 15, 2026 |
| 2nd | Apr 1 – May 31 | June 15, 2026 |
| 3rd | Jun 1 – Aug 31 | September 15, 2026 |
| 4th | Sep 1 – Dec 31 | January 15, 2027 |
Source: IRS When to pay estimated tax. The January payment can be skipped if you file your 2026 return by February 1, 2027 and pay the full balance with it.
Example: 1099 income only, $40,000 net profit (single)
SE tax: $40,000 × 0.9235 × 0.153 = $5,652
Adjusted income: $40,000 − half of SE tax ($2,826) = $37,174
Taxable income: $37,174 − $16,100 standard deduction = $21,074
Income tax: $12,400 at 10% ($1,240) + $8,674 at 12% ($1,041) = $2,281
Total: $5,652 + $2,281 = $7,933, or about $1,983 per quarterly payment
Simplified: no state tax, no credits, no qualified business income deduction. Use Form 1040-ES's worksheet for your real figure.
The safe harbor: how to be sure you won't be penalized
You generally avoid the underpayment penalty if you owe less than $1,000 after withholding and credits, or if your withholding and estimated payments add up to the smaller of 90% of this year's tax or 100% of last year's tax (110%if last year's AGI was above $150,000, or $75,000 if married filing separately). The prior-year test requires that last year's return covered 12 months. Details in our safe harbor guide.
If you're new to freelancing, the 100% (or 110%) of last year's tax test is the easy one. Your prior-year return is a known number, and your W-2 withholding may already be close.
W-4 adjustment vs. quarterly estimated taxes
| Raise W-4 withholding | Quarterly estimates | |
|---|---|---|
| Needs a W-2 job | Yes | No |
| Effort | One form, then automatic | Four payments a year |
| Uneven income | Fixed amount can over- or under-pay | Track each quarter's profit |
| Late-year fix | Yes: withholding counts as paid evenly | No: a missed quarter stays missed |
The two can be combined. Many people with a W-2 job raise withholding to cover the predictable part and pay a quarterly estimate only for a strong quarter.
1099-NEC, 1099-K and what counts as income
A client who pays you as a contractor reports it on Form 1099-NEC. For payments made after December 31, 2025, the reporting threshold rose from $600 to $2,000 in a year, per the IRS. Payment apps and marketplaces may send a 1099-K instead. A missing form doesn't change anything: every dollar of self-employment income is taxable, so keep your own records.
Common mistakes
- Forgetting self-employment tax. Income tax alone can understate the total by 14% of profit.
- Counting gross receipts instead of net profit. Expenses reduce both taxes, so track them from day one.
- Setting it once and forgetting it. If income changes, submit a new W-4 or adjust the next quarterly payment.
- Using Step 2 for a side gig. Step 2 is for a second job or a spouse's job, not for 1099 income. Read W-4 with two jobs if you have both.
- Missing the January payment because it belongs to the previous year's tax.
Frequently asked questions
How do I account for freelance income on my W-4?+
Estimate the tax on your net freelance income (income tax plus self-employment tax), divide it by your number of pay periods, and enter that amount in Step 4(c), Extra withholding. Alternatively, enter the side income in Step 4(a) so payroll withholds the income tax, and put the self-employment tax (15.3% on 92.35% of net profit) in Step 4(c), because Step 4(a) alone does not cover it. The IRS's own Tax Withholding Estimator can also work out the figure.
Do I pay self-employment tax on freelance income?+
Yes, if your net earnings from self-employment are $400 or more. The rate is 15.3% (12.4% Social Security and 2.9% Medicare), applied to 92.35% of your net earnings, which works out to about 14.13% of net profit. Your W-4 does not withhold it automatically, so you have to build it into Step 4(c) or pay it with estimated taxes.
Should I pay quarterly estimated taxes or adjust my W-4 for side income?+
If you have a W-2 job, raising your withholding is usually simpler because the tax is taken out of every paycheck automatically. If you have no job with withholding, or your side income is large or uneven, quarterly estimated payments (Form 1040-ES) are the tool. The IRS treats tax withheld from wages as paid evenly through the year, so extra withholding late in the year can also fix an earlier shortfall.
When are 2026 estimated tax payments due?+
April 15, 2026, June 15, 2026, September 15, 2026 and January 15, 2027. You can skip the January payment if you file your 2026 return by February 1, 2027 and pay the whole balance with it.
What is the safe harbor rule for freelancers?+
You generally avoid the underpayment penalty if you owe less than $1,000 after withholding and credits, or if your withholding plus estimated payments cover the smaller of 90% of this year's tax or 100% of last year's tax (110% of last year's tax if last year's AGI was above $150,000, or $75,000 if married filing separately).
Can I deduct half of my self-employment tax?+
Yes. Half of your self-employment tax is an adjustment to income on your return, so it reduces your income tax (not the SE tax itself). The estimates in this guide include it.
Do I need a 1099-NEC for my income to be taxable?+
No. All self-employment income is taxable whether or not you receive a form. For payments made after December 31, 2025, a business only has to send a 1099-NEC when it pays you $2,000 or more in the year (it was $600 before), but you still report every dollar.
I only freelance and have no W-2 job. Do I use a W-4?+
No. A W-4 only tells an employer how much to withhold from your wages. If you have no wages, you pay your income tax and self-employment tax through quarterly estimated payments with Form 1040-ES.
Sources: Form W-4 (2026), IRS Topic 554, Self-employment tax, IRS estimated tax FAQs, Publication 505. General information, not tax advice.
Key terms in this article
Wondering what your W-2 job actually pays after taxes? Calculate your take-home pay across all income sources with our free salary calculator. Take-Home Pay Calculator →
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