The first time someone goes from a W-2 job to freelancing and files their tax return, the same shock hits: their tax bill is way bigger than they expected. They knew about federal income tax. They knew about state income tax. The thing they didn't know about — the line item that nearly doubles their bill in some years — is self-employment tax.
Here's what it actually is, who has to pay it, why it exists, and the legal deduction that softens it.
What self-employment tax actually is
Self-employment (SE) tax is the freelancer version of FICA — the Social Security and Medicare taxes that get withheld from every W-2 paycheck.
On a W-2 job, those taxes total 15.3%:
- 12.4% for Social Security (capped at the annual wage base)
- 2.9% for Medicare (no cap)
But your employer pays half of that (7.65%) on your behalf, and you only see the other half (7.65%) come out of your paycheck. Most W-2 workers don't even realize the employer half exists.
When you become self-employed, you're both the employer and the employee. So you owe the full 15.3% on your net business earnings — that's self-employment tax. It's on top of federal income tax, on top of state income tax, on top of any city tax.
Why it exists
Social Security and Medicare are pay-as-you-go programs. Workers today fund retirees today. That works as long as everyone contributing to wages is also contributing to FICA. When the self-employment economy started growing in the 20th century, Congress added SE tax (via the Self-Employment Contributions Act, 1954) so freelancers would build up Social Security credits the same way W-2 workers do.
The upside: you're still earning Social Security quarters for every dollar of SE tax you pay. When you retire, you'll collect benefits.
Who has to pay it?
Anyone with $400 or more in net earnings from self-employment in a tax year. That's the threshold. Above $400, you owe SE tax. Below, you don't.
This catches:
- Sole proprietors filing Schedule C
- Single-member LLC owners (treated as sole proprietors by default)
- Partners in a partnership (on guaranteed payments + distributive share)
- 1099 contractors and gig workers (Uber, DoorDash, Etsy sellers, OnlyFans, freelance dev/design/writing)
- Most farmers
- People with side hustles netting more than $400/yr
Notably not subject to SE tax:
- S-corp shareholder distributions (only the salary portion is — that's why owner-operators sometimes elect S-corp status, but it has costs and complications)
- Rental real-estate income (passive, generally)
- Royalties on intellectual property held passively
- Investment income (capital gains, dividends, interest)
The actual math
The IRS computes SE tax in three steps:
- Take net earnings from self-employment (Schedule C profit, or partnership earnings) and multiply by 92.35% — this is the "net SE earnings" figure. The 7.65% haircut exists because employees only pay FICA on 92.35% of their wages (the employer's half isn't taxed). It keeps the math fair across W-2 and SE.
- Multiply net SE earnings by 12.4% to get the Social Security portion — but only up to that year's Social Security wage base (around $168k–$180k, published annually by the SSA; check ssa.gov for the current figure).
- Multiply net SE earnings by 2.9% to get the Medicare portion. No cap.
Add steps 2 and 3. That's your SE tax. It goes on Schedule SE, then flows to Schedule 2.
Worked example
Say you have a Schedule C net profit of $80,000.
- $80,000 × 92.35% = $73,880 (net SE earnings)
- $73,880 × 12.4% = $9,161.12 (Social Security portion)
- $73,880 × 2.9% = $2,142.52 (Medicare portion)
- Total SE tax: $11,303.64
That's on top of federal income tax. If you're in the 22% bracket on your taxable income, you'd owe roughly another $14,000 in income tax — call it $25,300 total federal tax on $80k of profit. That's the sticker-shock everyone feels their first year.
The deduction that softens it
The IRS lets you deduct half of your SE tax as an above-the-line deduction. It goes on Schedule 1, line 15 (the line is sometimes called the "deductible part of self-employment tax").
In the example above, you'd deduct $5,651.82 from your adjusted gross income before computing federal income tax. At a 22% bracket, that saves you about $1,243 in income tax. The deduction doesn't reduce SE tax itself — it reduces the income tax you pay on the income that funded your SE tax. Loose translation: it gets you back the income tax you would have paid on the "employer half" of FICA.
Every Schedule C filer is entitled to this. Tax software handles it automatically. If you're doing your taxes by hand, do not skip it.
The Additional Medicare Tax (high earners)
On top of regular Medicare (2.9%), high earners owe an extra 0.9% Additional Medicare Tax on the portion of their wages + SE income that exceeds:
- $200,000 if filing single
- $250,000 if filing married jointly
- $125,000 if filing married separately
It hits regardless of whether the income comes from W-2 wages, SE earnings, or both. Computed on Form 8959. Only affects freelancers earning into the top brackets, but worth knowing it's out there before it surprises you.
Quarterly estimates: SE tax counts
The 25–30% "set aside per dollar of profit" rule of thumb that's common in freelance circles is high partly because SE tax pushes the effective rate up. If you only set aside enough to cover federal income tax (15–22% in most brackets), you'll be short by exactly the SE-tax amount when April rolls around.
See our walkthrough on calculating quarterly estimated taxes for the math and the safe-harbor shortcut that avoids underpayment penalties.
The S-corp question (briefly)
Above ~$80k–$100k of consistent profit, some freelancers elect S-corp tax treatment for their LLC. The mechanic: pay yourself a "reasonable salary" (W-2, FICA-taxed) and take the rest as a distribution (not SE-taxed). Saves SE tax on the distribution portion.
Costs to weigh: payroll setup ($30–60/mo), separate filing (Form 1120-S), required "reasonable salary" (the IRS will challenge artificially low salaries), and added complexity on retirement contributions, QBI calculations, and state-level quirks.
Rough rule: probably not worth it under ~$60k profit; possibly worth it $80k–$100k+; almost certainly worth a CPA conversation $150k+. Don't DIY this — the implementation details are where it goes wrong.
What SE tax does NOT pay for
A common confusion: SE tax funds Social Security and Medicare only. It does not fund:
- Federal unemployment insurance (you're ineligible)
- State unemployment insurance (same)
- Workers' compensation (you must self-fund)
- Disability insurance (consider a private policy)
- Paid family leave (varies by state)
Translation: if you stop being able to work, the only safety net SE tax has built for you is Social Security disability — which is real but slow and means-tested. Most freelancers earning over ~$70k should look at a private long-term disability policy.
The mental model
The cleanest way to think about SE tax: it's the price of independence. You traded an employer who paid half your FICA, a 401(k) match, group health insurance, and unemployment coverage for the freedom to set your own rates and pick your own clients. The trade is usually worth it — but you have to price it in.
Practically, that means: when you're setting freelance rates, build in 15–20% for SE tax on top of whatever you'd have charged as a W-2 cost-equivalent. A $50/hr W-2 equivalent is roughly $65–$70/hr as a freelancer. Lower than that and you're paying yourself out of your own retirement.
Ledgentry tracks SE tax in real time as your income lands — so you always know what your actual after-tax rate is, not the gross one your client sees on the invoice.