How to Calculate Self-Employment Tax in 2026

A plain-English walkthrough of Schedule SE math, with worked examples, the 2026 IRS thresholds, and the common mistakes that cost freelancers thousands.

The one-sentence version

Self-employment tax is 15.3% of 92.35% of your net self-employment earnings, capped at a $168,600 Social Security base, with an extra 0.9% Medicare surtax above $200,000 (single) or $250,000 (married filing jointly). That's the whole formula. Everything below is explanation, examples, and the edge cases that trip people up.

Why self-employment tax exists at all

When you're a W-2 employee, your paycheck has two payroll-tax lines: FICA (Social Security 6.2% + Medicare 1.45% = 7.65%) comes out of your pay, and your employer pays an identical 7.65% on top of your salary that you never see. Congress designed Social Security and Medicare to be funded half by the worker and half by the employer.

When you work for yourself, there's no employer to put up the other half. The IRS's answer: you're both. You pay the 15.3% combined rate yourself. That's the entire concept of self-employment tax — it's not a punishment on freelancers, it's the same total contribution to Social Security and Medicare that a salaried worker makes; you just have to write the check directly instead of having it deducted from your paycheck.

The 2026 numbers you need to memorize

• Combined rate: 15.3% (12.4% Social Security + 2.9% Medicare)
• Social Security wage base: $168,600 — above this, the 12.4% portion stops
• 92.35% reduction factor: multiply your net earnings by this before applying the rate
• Additional Medicare surtax: extra 0.9% above $200k single / $250k MFJ / $125k MFS
• Minimum owed: nothing if net earnings are under $400
• Deductible half: 50% of your SE tax (not the additional Medicare piece) is deductible on your 1040

The five-step calculation

Step 1 — Calculate net self-employment earnings

Take your gross business income and subtract all your legitimate business expenses. This is your Schedule C profit — the same number that flows onto your 1040 as "business income."

Example: Gross freelance income of $95,000, minus $18,000 in expenses (software $2,400, home office $1,800, mileage 6,500 miles × $0.67 = $4,355, internet and phone $1,200, continuing education $800, professional services $2,000, supplies and misc $5,445) = net earnings of $77,000.

Step 2 — Apply the 92.35% reduction

Multiply net earnings by 0.9235. This is the weird step that nobody explains well, so here's the explanation: if you were a W-2 worker making $77,000, the employer half of FICA (7.65%) would come out of the employer's budget, not yours. By multiplying by 92.35% (which is 100% − 7.65%), the IRS is pretending that employer-half doesn't exist for the purpose of calculating your SE tax, so your tax bill approximately matches what you'd owe if you were an employee.

Continuing the example: $77,000 × 0.9235 = $71,110 taxable base.

Step 3 — Apply the 12.4% Social Security rate (with cap)

Multiply the taxable base by 12.4%, but only on the portion that falls within the $168,600 Social Security wage base. If you also have W-2 wages this year, those wages already used up part of the base, so subtract them first.

Example: $71,110 is well under $168,600, so the full amount counts. $71,110 × 12.4% = $8,818 Social Security portion.

Above the cap, this portion stops. A freelancer earning $300,000 net doesn't pay 12.4% on the full $300,000 — only on the first $168,600.

Step 4 — Apply the 2.9% Medicare rate (no cap)

Multiply the full taxable base by 2.9%. Medicare has no wage cap.

Example: $71,110 × 2.9% = $2,062 Medicare portion.

Step 5 — Add Additional Medicare if applicable

If your taxable base plus any W-2 wages exceeds your filing-status threshold, add 0.9% on the amount above the threshold.

Example: Single freelancer at $71,110 — well under the $200,000 single threshold, so $0 additional Medicare.

Total SE tax: $8,818 + $2,062 = $10,880.

The deductible half (used to reduce your income tax, not your SE tax): $10,880 × 50% = $5,440. That $5,440 comes off your AGI on Form 1040 line 15.

Worked example #2: the wage-base cap

A freelance consultant earns $220,000 gross with $25,000 in expenses, single, no W-2 job.

• Net earnings: $195,000
• Taxable base: $195,000 × 0.9235 = $180,082
• Social Security: only the first $168,600 of taxable base counts → $168,600 × 12.4% = $20,906
• Medicare: $180,082 × 2.9% = $5,222
• Additional Medicare: $180,082 is under the $200,000 single threshold (remember, the threshold is applied to the taxable base, not gross or net earnings) → $0
• Total SE tax: $26,128

Deductible half: $13,064.

Worked example #3: freelancer with a W-2 day job

Someone earns $120,000 in W-2 wages from a full-time job and also freelances on the side, netting $40,000 after expenses, single filer.

• Taxable base: $40,000 × 0.9235 = $36,940
• Social Security base remaining: $168,600 − $120,000 (already used by W-2 wages) = $48,600
• Social Security portion: min($36,940, $48,600) × 12.4% = $36,940 × 12.4% = $4,581
• Medicare portion: $36,940 × 2.9% = $1,071
• Additional Medicare: combined base ($36,940 + $120,000 = $156,940) is under $200,000 single threshold → $0
• Total SE tax: $5,652

Had this person earned another $50,000 in wages before the SE income, the Social Security base would have been used up and the 12.4% portion would have dropped to zero — a significant savings. This is why some people deliberately max out their W-2 Social Security at their day job before ramping up side income.

Seven mistakes that cost freelancers real money

1. Forgetting the 92.35% reduction. Calculating 15.3% of gross net earnings directly inflates your tax by about 1.15%. On a $100k net profit, that's ~$1,175 you didn't actually owe.
2. Not tracking mileage. The 2026 standard mileage rate is $0.67 per business mile. A rideshare driver putting 20,000 business miles on a car is leaving $13,400 of deductions on the table — and those deductions save roughly 15.3% in SE tax plus your marginal income tax rate. A $13,400 deduction saves a 22% bracket freelancer over $5,000.
3. Missing quarterly payments. The IRS charges a ~7% annualized underpayment penalty. It's small-ish, but it compounds and adds friction at tax time. Just set up EFTPS and pay them.
4. Not separating business and personal accounts. Makes it almost impossible to find all your deductions at year-end and is a huge audit risk.
5. Trying to "1099 themselves" as an S-corp too early. The S-corp play has real payroll and filing costs (~$1,500/year) that only pay off once you have enough profit. Rule of thumb: consider it seriously above ~$50,000 net profit, act on it above ~$80,000.
6. Confusing the deductible half of SE tax with actually paying less SE tax. The deduction reduces your income tax, not your SE tax. Many people assume "half off" and are shocked at the real bill.
7. Ignoring retirement contributions. A Solo 401(k) can absorb up to $70,000/year of self-employed income in 2026 and dramatically lowers your income tax. Doesn't touch SE tax, but it's still the biggest tax planning lever available to most freelancers.

When an S-corp election makes sense

An S-corp election lets you split your income between "reasonable salary" (subject to FICA on the payroll side, basically the same 15.3%) and "distributions" (subject to income tax but not SE tax). The savings compound as your profit grows, but the overhead is real: quarterly payroll filings, an annual 1120-S, state filing fees, and the headache of actually running payroll for yourself.

Rough guidance: below $40k in net profit, skip it. Between $40k and $80k, it's a close call — run the exact numbers. Above $80k, it usually wins by $2k–$5k per year after all the overhead. Above $150k, the savings can hit $8k–$12k per year. This isn't tax advice — it depends heavily on your state, your reasonable-salary defense, and whether you're comfortable with the operational overhead. Talk to a CPA before filing the 2553.

Frequently asked

Ready to run the numbers on your own income? Use the self-employment tax calculator.