The 15.3% surprise every first-year freelancer meets
The invoice said $4,500. The checking account received $4,500. So April's tax bill came as an ambush: roughly a third of it was never yours to spend. Self-employment tax is the line item that separates freelancing-as-hobby from freelancing-as-business, and it works differently from the payroll withholding most people grew up on — no employer half, no automatic deposit, no reminders until the IRS sends an unwelcome letter.
Here is the part that stings. An employee pays 7.65% of wages in FICA and never sees the employer's matching 7.65%. A self-employed person pays both halves — 15.3% — on net business profit. The cushion is that it applies to 92.35% of net earnings rather than all of it, and half of the total is deductible against income tax. Most calculators show the big scary number and hide the cushion. This one shows every piece, because the deduction is where a meaningful refund quietly lives.
Enter your net profit — revenue minus expenses, the Schedule C number, not gross receipts — and the calculator returns the SE tax, both component parts, the wage-base interaction, the additional Medicare surtax if your earnings are high enough, and the deductible half. It runs entirely in your browser, and it exists because this particular tax rewards people who understand it a full year before they file it.
Getting a number out of the calculator
Five entries, and the tool does the Schedule SE walk for you:
Enter net self-employment profit
Business revenue minus deductible business expenses — the bottom line of Schedule C. Use the projected year if you are planning ahead, or last year's figure if you are checking a completed return.
Add W-2 wages if you have a day job
Social Security wages from employment count against the same $184,500 ceiling. The calculator needs them to know whether your 12.4% portion applies in full, partially, or not at all.
Pick your filing status
This matters only at higher incomes, where the additional 0.9% Medicare tax starts at $200,000 single or $250,000 married filing jointly. Below those thresholds the choice changes nothing.
Read the breakdown
You get the 92.35% net-earnings figure, the 12.4% Social Security component, the 2.9% Medicare component, any additional Medicare tax, and the total.
Note the deduction line
Half of the total appears as your above-the-line deduction — carry it into your income tax estimate, or hand it to whoever prepares your return.
How SE tax is actually built: 92.35%, 12.4%, 2.9%
Self-employment tax is the self-employed version of FICA, and its arithmetic has three quirks that catch people who learned payroll math as employees. The method below is the one Schedule SE implements and the one this calculator applies.
Quirk one: the 92.35% multiplier. Net profit is multiplied by 0.9235 before anything else happens. The logic is symmetry with employment — employers deduct their half of payroll tax, so the self-employed compute their tax on the equivalent of wages after the employer-side deduction. On $80,000 of net profit, the tax base is $80,000 × 0.9235 = $73,880, formally called net earnings from self-employment.
Quirk two: the Social Security ceiling. The 12.4% Social Security component applies only up to the annual taxable maximum. The Social Security Administration announced $184,500 for 2026, up from $176,100 in 2025 — the base is re-set each October, so verify it before you file. Above the ceiling, the 12.4% simply stops. If you also have W-2 wages, they consume the ceiling first: $190,000 of employment wages means your side business pays no Social Security tax at all, only Medicare.
Quirk three: Medicare never stops. The 2.9% Medicare component has no wage base — it applies to every dollar of net earnings, at any income. Above $200,000 single or $250,000 married filing jointly, an additional 0.9% Medicare tax stacks on top, reported on Form 8959. Those thresholds are fixed in statute and are not indexed for inflation, so they reach more businesses every year.
The floor is small but real: net earnings below $400 for the year mean no SE tax at all. Above it, everything computed here flows to Schedule SE, and the result lands on your Form 1040 alongside income tax — two separate taxes that happen to be mailed in one envelope.
Then there is the refund-the-flavor deduction. One-half of SE tax is deductible as an income adjustment — above the line, available without itemizing. It reduces AGI, which in turn softens income tax and can pull other AGI-sensitive thresholds into reach. On a $11,303.64 tax bill the deduction is $5,651.82; for a taxpayer in the 22% bracket that is about $1,243 back. It is not a rebate of the SE tax itself, but it is real money that generic calculators routinely leave on the table.
$80,000 of net income, computed line by line
A freelance developer finishes the year with $80,000 of net Schedule C profit, no other wages, single filing. Here is the entire SE tax computation, shown the way Schedule SE would show it:
Input
Net self-employment profit: $80,000 · Filing status: single · W-2 Social Security wages: $0
Output
Net earnings: 80,000 × 0.9235 = $73,880.00 Social Security (12.4%): 73,880 × 0.124 = $9,161.12 Medicare (2.9%): 73,880 × 0.029 = $2,142.52 Total self-employment tax: $11,303.64 Deductible half: $5,651.82 Income-tax value at 22% bracket: about $1,243
Every number is checkable by hand: multiply 73,880 by 0.124, then by 0.029, then add. The practical takeaways are that the effective rate on the original $80,000 is 14.13%, and that the deduction alone claws back roughly eleven percent of the tax bill's income-tax equivalent. Neither fact appears on a generic '15.3% calculator.'
Input
Net self-employment profit: $250,000 · Filing status: single · W-2 Social Security wages: $0
Output
Net earnings: 250,000 × 0.9235 = $230,875.00 Social Security (12.4% on first $184,500): $22,878.00 Medicare (2.9% on all $230,875): $6,695.38 Total: $29,573.38 Deductible half: $14,786.69 Additional Medicare (0.9% on earnings over $200,000): $277.88
Past the ceiling the geometry changes: only Medicare grows. Between $184,500 of net earnings and $250,000 of profit here, the marginal SE rate drops from roughly 14.1% to 2.9% — plus the 0.9% surtax over the threshold. High earners who notice this often start asking about S-corporations, and that question has its own calculator, linked below.
Input
W-2 Social Security wages: $190,000 · Side-business net profit: $30,000 · Filing status: single
Output
Net earnings from side business: 30,000 × 0.9235 = $27,705.00 Social Security portion: $0 — wages already exceed the $184,500 base Medicare (2.9%): $803.45 Total SE tax: $803.45
The side-gig surprise is pleasant for once: wages above the ceiling mean the 12.4% never applies. Only $803.45 of Medicare tax is due on the whole $30,000 of side profit. Income tax on the profit is a separate conversation — and the additional 0.9% may still reach combined earnings past $200,000.
Sole proprietor versus S-corp: where SE tax fits
Self-employment tax is the engine of the most common entity question in freelancing: should this LLC stay a disregarded entity, where all profit pays SE tax, or elect S-corporation taxation, where only a reasonable salary pays FICA? The short version of the trade:
| Structure | How profit is taxed | Where it hurts | Where it pays |
|---|---|---|---|
| Sole prop / single-member LLC | 15.3% SE tax on 92.35% of all net profit | Above roughly $60–80k profit the 14.1% effective drag compounds | Zero payroll admin, no salary documentation, simplest filing |
| LLC electing S-corp taxation | FICA on a reasonable salary only; distributions carry no payroll tax | Payroll service, extra return, unemployment insurance, reasonable-comp scrutiny | At $100k profit with a $50k salary, payroll tax drops from $14,130 to $7,650 |
The employee comparison is worth a glance too. A W-2 worker at the same income pays 7.65% of wages while the employer quietly matches it — the self-employed pay the combined 14.13% effective load themselves and get the half deduction as consolation. You can see the employee-side arithmetic in the paycheck calculator if you want the side-by-side.
The quarterly rhythm that keeps the penalty away
Nobody withholds self-employment tax for you — no employer, no client, no platform. The IRS expects you to deliver it yourself in four installments: April 15, June 15, September 15, and January 15 of the following year. The quarters are not even: the June payment covers only two months (April and May), the January one covers four, which surprises everyone the first time they annualize by hand.
The size of each check has a get-out-of-jail card called the safe harbor. Skip the underpayment penalty entirely by paying, across withholding plus estimates, the smaller of 90% of this year's total tax or 100% of last year's total tax — 110% of last year's if your prior-year adjusted gross income topped $150,000. The prior-year route is the one disciplined freelancers use in a boom: it fixes your quarterly amount in January instead of forcing a guess at income you have not earned yet.
Input
Last year's total tax (withholding + estimates): $12,000 · Last year's AGI: $95,000 · This year's projected net profit: up from $68,000 to $110,000
Output
Safe harbor amount: $12,000 ÷ 4 = $3,000 per quarter (100% rule — AGI was under $150,000). Pay that on all four dates and no underpayment penalty applies for the year, whatever April's final bill says. The remaining balance is due with the return, penalty-free.
Income that arrives unevenly has its own relief: the annualized installment method on Form 2210 Schedule AI matches each payment to the income actually earned by that date, so a consultant whose entire year lands in October is not penalized for small April and June checks. The trade is paperwork — the schedule makes you reconstruct income period by period, which is exactly as fun as it sounds.
Where estimates stop being advice
This calculator is an educational estimate, and we would rather flag its seams than let you discover them in an audit. What it deliberately leaves out:
- Income tax. SE tax is one of two taxes on the same profit; federal income tax, state income tax, and any local levies sit on top. Use the quarterly estimated tax calculator to size the combined payment.
- The QBI deduction's interaction. The qualified business income deduction is computed after SE tax, and the SE deduction reduces the income it applies to — a real but second-order effect we do not attempt.
- Special rules. Farmers and fishermen, church employees with income of $108.28 or more, and notary income exempt from SE tax all follow their own branches of Schedule SE.
- Loss years and multiple businesses. Profits and losses across your ventures net together before the tax applies; a losing partnership can shelter a profitable sole proprietorship on the SE side.
- The wage base moves every October. We carry the announced 2026 figure, $184,500; confirm it against the SSA's contribution-base page before filing any return based on this estimate.
Who runs this calculation, and how often
First-year freelancers arrive in two moods: April panic, having just discovered the tax exists, and December planning, having heard about it from a friend who survived the April version. The December people have the better year. Gig workers — drivers, delivery, task platforms — run it quarterly on cumulative net profit, usually alongside a mileage deduction that shrinks the base before this tool ever sees it.
Etsy and eBay sellers use it to size the tax on net profit once fees and cost of goods come out, which is also where the hobby-versus-business question lives: a genuine profit motive makes this calculation real, a hobby that occasionally sells does not reach Schedule C. Rideshare drivers, tutors with 1099s, and consultants all land on the same form eventually.
The most disciplined users rerun it three times a year: once when setting rates — the freelance rate calculator consumes this number directly — once mid-year when the profit picture firms up, and once before each quarterly payment so the check matches the reality instead of the January forecast.
Five ways people get this number wrong
The calculator's inputs are simple, which makes the input errors stand out. These five account for most of the wrong numbers we hear about:
- Running it on gross receipts. The base is Schedule C net profit — revenue minus expenses — not the top-line number in the payment app. On $80,000 of receipts with $22,000 of deductible expenses, the SE tax is about $8,195, not the $11,304 that a gross-receipts entry would report. The $3,100 difference is the tax on money you already spent on the business.
- Treating the deduction as a credit. The deductible half shaves taxable income at your marginal rate, not the tax bill dollar-for-dollar. A $5,651.82 deduction in the 22% bracket returns roughly $1,243 — real money, but a third of what people imagine when they hear 'deduct half your SE tax.'
- Forgetting the $400 floor cuts both ways. Net earnings under $400 owe no SE tax, but the profit still counts as taxable income, and a $380 year still belongs on the return. The floor exempts the tax, not the reporting.
- Saving only for income tax. The workable rule of thumb for a mid-range sole proprietor is 25–30% of net profit set aside for everything federal — SE tax plus income tax — plus whatever your state takes. Saving exactly 15.3% covers half the bill and turns every April into an emergency.
- Quoting 15.3% as the whole burden. Self-employment tax is one of two federal taxes on the same profit. A freelancer in the 22% income-tax bracket carries the 14.13% effective SE load on top of it — call it 36 cents on the marginal dollar before the state takes its share, and price accordingly.
The pattern behind all five: each one is an arithmetic shortcut that feels safe and is not. The fix in every case is the same — start from net profit, apply the multiplier, cap, and surtax in order, and keep the deduction in the income-tax column where it belongs. That sequence is the calculator's entire logic, which is the argument for running the numbers twice a year instead of doing them in your head at midnight in April.
Browser-only by design
Your net profit is the single most sensitive number your business produces, and it is also the number most tools happily ship to a marketing database the moment you type it. This calculator does not. The entire Schedule SE method — multiplier, cap, surtax, deduction — is plain JavaScript executing on your device. No account, no upload, no persistent storage, no retargeting pixels with opinions about your revenue.
The practical side effects: it is instant, it works on a plane, and you can run a dozen scenarios without any of them existing anywhere but the tab you close afterward. Estimate freely. Nothing is watching.
SE tax questions, answered plainly
What is the self-employment tax rate for 2026?
The combined rate is 15.3% — 12.4% for Social Security plus 2.9% for Medicare — applied to 92.35% of your net self-employment earnings. The Social Security portion stops at the taxable maximum, which the Social Security Administration set at $184,500 for 2026 (up from $176,100 in 2025). The Medicare portion has no cap, and an additional 0.9% applies above $200,000 single or $250,000 married filing jointly.
Why is the tax calculated on 92.35% of my net profit instead of 100%?
Employers can deduct their half of FICA payroll taxes, so self-employed people get the equivalent break: net profit is multiplied by 0.9235 before the 15.3% applies. On $80,000 of net profit that means $73,880 of net earnings from self-employment, and the tax is computed from that figure on Schedule SE.
Can I deduct half of my self-employment tax?
Yes. One-half of SE tax is claimed as an income adjustment — a deduction that reduces AGI, above the line, whether or not you itemize. On $80,000 of net profit the SE tax is $11,303.64 and the deductible half is $5,651.82, which at a 22% marginal rate is worth roughly $1,243 in income-tax savings. It is a deduction, not a credit, so the value depends on your bracket.
Do I owe self-employment tax on my side business if I also have a W-2 job?
Generally yes, once net self-employment profit reaches $400 for the year. The twist is the wage base: your W-2 Social Security wages count first, so a $190,000 day job already exceeds the 2026 maximum and your side business pays only the 2.9% Medicare portion. Schedule SE walks through exactly this interaction, and the calculator includes a wages field to handle it.
What happens if my business shows a loss?
Self-employment tax applies to net profit, so a Schedule C loss produces no SE tax for that year. You also do not get to bank the zero against future years — each year stands on its own net profit. Multiple businesses aggregate: profitable and losing ventures are netted together on Schedule SE before the tax is computed.
Does my state tax self-employment income too?
Your state will tax the profit as income through its normal income tax — that part is unavoidable. The 15.3% SE tax itself is federal, and most states do not add a separate self-employment levy on top. A few states have entity-level taxes that can matter for LLCs and S-corporations, which is a structure conversation for a CPA.
Is this calculation official tax advice?
No. It is an educational estimate built from the published Schedule SE method — the 92.35% multiplier, the 12.4% and 2.9% components, the announced 2026 wage base, and the deductible half. Filing decisions belong with your own numbers on the actual forms, ideally reviewed by a tax professional.
Do S-corporation owners pay self-employment tax?
Not on their salary — that runs through standard FICA payroll withholding instead — and not on distributions, which is precisely the reason people elect S-corp taxation at higher profits. The comparison math, including the payroll costs that offset the savings, lives in the LLC vs S-Corp calculator.
When are quarterly self-employment tax payments due?
April 15, June 15, September 15, and January 15 of the following year. The windows are uneven — the June payment covers only April and May, while the January payment covers the final four months — so a business that annualizes income by period uses Form 2210 Schedule AI rather than dividing by four.
What is the safe harbor rule for estimated taxes?
Pay the smaller of 90% of this year's total tax or 100% of last year's total tax through withholding and timely estimates, and the underpayment penalty cannot touch you. The prior-year percentage rises to 110% when your prior-year adjusted gross income exceeded $150,000. Last year's total tax, divided by four, is the number most self-employed people send each quarter.
Can extra withholding from a W-2 job cover my self-employment tax?
Yes, and the mechanics favor it. Withholding is treated as paid evenly across the year no matter when it was actually withheld, unlike estimated payments which count only on their own dates. A freelancer with a part-time job can raise the W-4 withholding in November and December to absorb the side business's SE tax, curing an earlier shortfall in a way a late estimated payment cannot.
Sources
The method above follows the IRS and SSA primary documents:
Sources and further reading
- IRS — About Schedule SE (Self-Employment Tax)(irs.gov)
- SSA — Contribution and benefit base (taxable maximum)(ssa.gov)
- IRS — About Form 8959 (Additional Medicare Tax)(irs.gov)
- IRS — Self-Employed Individuals Tax Center(irs.gov)
We cite primary sources (standards bodies, government agencies, official documentation) wherever they exist so you can verify every number on this page yourself.