Self-Employment Tax: Paying Both Halves, Explained

By Tom, CPA · Updated October 27, 2026

Part of: Tax Planning

TL;DR: SE tax is 15.3% of 92.35% of net self-employment profit, with the 12.4% Social Security portion capped at $184,500 for 2026 ($192,300 for 2027). Half is deductible. Business expenses and, at higher profits, an S corp can reduce it.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

Congratulations on becoming your own boss. Your new boss would like you to know that you now pay both halves of Social Security and Medicare tax, a combined 15.3%, on top of income tax. Employees never notice this, because their employer quietly pays half and the other half disappears from the paycheck before they can get attached to it. The self-employed get the bill directly, usually in April, usually with a facial expression.

The tax code is 4 million words long; you need about 400 of them to understand self-employment (SE) tax. This guide walks through the 92.35% calculation, the 2026 and 2027 Social Security wage base, the additional Medicare tax, the deduction for half of SE tax, and strategies that legally reduce it. Figures are as of Oct 2026.

CPA Warning Label: Paying yourself too little through an S corp, or hiring family for fake work, invites IRS scrutiny. Document real work and reasonable pay.

The 92.35% calculation

SE tax is calculated on Schedule SE. The steps:

1. Start with net profit from self-employment (Schedule C, farm income, or partnership self-employment earnings).
2. Multiply by 92.35%. This mimics the employer-side deduction an employee's wages never include. The result is "net earnings from self-employment."
3. Apply 12.4% Social Security tax up to the annual wage base, and 2.9% Medicare tax on all of it.

If net earnings from self-employment are less than $400, no SE tax is due. Why 92.35%? Because 100% minus half of 15.3% is 92.35%. Your profit is treated as if your imaginary employer had already deducted its share.

These rows assume no W-2 wages and are below the Social Security wage base.

The Social Security wage base

The 12.4% Social Security piece only applies up to the contribution and benefit base. Per the Social Security Administration, the base is $184,500 for 2026 and $192,300 for 2027. The 2.9% Medicare piece has no cap.

The cap is shared with W-2 wages. If you earn $150,000 at a day job and have $60,000 of side-business net earnings, only $34,500 of the side income is exposed to the 12.4% in 2026; the rest pays only Medicare. Schedule SE handles this by subtracting Social Security wages already reported on your W-2.

Additional Medicare tax

An extra 0.9% Medicare tax applies to combined wages and self-employment income above $200,000 (single), $250,000 (married filing jointly) or $125,000 (married filing separately). Those thresholds are set by statute and are not indexed for inflation. It is calculated on Form 8959.

The deduction for half of SE tax

You deduct half of your SE tax as an adjustment to income on Schedule 1. It lowers AGI and income tax, but it does not lower SE tax itself. On $100,000 of profit, SE tax is about $14,130 and the deduction is about $7,065. At a 22% bracket, that deduction saves about $1,554 of income tax.

The half-SE deduction also reduces qualified business income for the QBI deduction. Our QBI deduction guide covers that interaction.

Legal ways to reduce SE tax

1. Deduct every legitimate business expense

SE tax is calculated on net profit, so every ordinary and necessary business expense on Schedule C reduces it, at roughly 14% (15.3% × 92.35%) on top of income tax savings. Our Schedule C deductions checklist covers the common ones: home office, vehicle, equipment, software, insurance and professional fees.

2. Understand what does not reduce SE tax

Several deductions reduce income tax but not SE tax: SEP and solo 401(k) contributions for yourself, the self-employed health insurance deduction, HSA contributions and the QBI deduction. People are often surprised that a big solo 401(k) contribution leaves SE tax untouched.

3. Consider an S corporation election at higher profits

An S corporation owner who works in the business takes a reasonable salary subject to payroll tax, and remaining profit passes through without SE tax. The savings must outweigh payroll costs, state fees, a separate return and other admin. See our S corp break-even guide and reasonable salary guide. Underpaying salary to dodge payroll tax is a well-known audit issue.

4. Rental income is generally not subject to SE tax

Rental real estate income reported on Schedule E is generally not subject to SE tax, unless you provide substantial services to guests, like a hotel would. Short-term rentals with hotel-like services can land on Schedule C and owe SE tax. Our self-rental rules guide covers related traps when you rent property to your own business.

5. Hire your children, carefully

A sole proprietor's payments to their own child under 18 for real work are generally not subject to Social Security and Medicare taxes. The work must be genuine, paid at a reasonable rate, and documented. This does not apply to the same degree for S corporations or partnerships with non-parent owners.

Illustration: a side hustle on top of a day job

Jordan is single and earns $120,000 in W-2 wages in 2026. Jordan also runs a design business with $40,000 of net profit.

• Net earnings from self-employment: $40,000 × 92.35% = $36,940
• Social Security room left under the $184,500 base: $184,500 − $120,000 = $64,500, so all $36,940 is exposed
• Social Security piece: $36,940 × 12.4% = $4,581
• Medicare piece: $36,940 × 2.9% = $1,071
• Total SE tax: about $5,652
• Deduction for half: about $2,826

Jordan's combined wages and SE income stay under $200,000, so no additional Medicare tax. Now suppose Jordan's W-2 wages were $190,000 instead. Social Security wages already exceed the base, so the 12.4% piece is zero and SE tax would be about $1,071 of Medicare, plus 0.9% additional Medicare tax on the amount over $200,000. Same side hustle, very different SE tax bill.

Illustrations use rounded figures and ignore state taxes.

Common SE tax mistakes

• Forgetting SE tax exists. New freelancers often budget for income tax at their bracket and are blindsided by an extra 14% or so. At low incomes SE tax can exceed income tax entirely, because the standard deduction shelters income tax but not SE tax.
• Ignoring the wage base interaction. If you also have a W-2 job, make sure Schedule SE picks up your Social Security wages so you do not pay 12.4% twice above the cap. Software usually handles this, but only if you enter the W-2 first.
• Misreading 1099-K and 1099-NEC totals. Platform forms report gross receipts. SE tax is on net profit after expenses, so unrecorded expenses cost you twice.
• Treating hobby income as business income, or the reverse. Hobby income is not subject to SE tax, but hobby expenses are not deductible. Real businesses with a profit motive file Schedule C.
• Skipping SE tax to "save" Social Security. SE tax also earns Social Security credits and future benefits. Very low reported earnings can leave gaps in your record. Reducing tax legally is fine; underreporting is not.
• Married couples splitting a business informally. A business owned and run by spouses may be a partnership, or may qualify as a qualified joint venture, which splits SE earnings between both spouses. Who reports the income affects whose Social Security record gets credit.

The quick sanity check: multiply your net profit by about 14.1% (15.3% × 92.35%). If your SE tax line looks wildly different and you are under the wage base, something was entered wrong.

Paying SE tax during the year

SE tax is not withheld. You pay it through quarterly estimated payments (Form 1040-ES) or by increasing withholding at a W-2 job. For 2026 tax year estimates, due dates are generally April 15, June 15 and September 15 of 2026, and January 15, 2027, adjusted when a date falls on a weekend or holiday. Underpaying can trigger the estimated tax penalty; see refund vs owe for the safe harbors.

A practical habit: move 25% to 30% of every client payment into a separate tax savings account the day it arrives. That number covers SE tax plus a moderate federal income tax rate for many freelancers; your mileage, literally, may vary.