Self-Employment Tax in the US: The 15.3% Nobody Warned You About

The most common shock for new American freelancers is not the income tax rate — it is self-employment tax. Employees never see the employer half of their payroll tax, so the first year of contracting feels like a 15.3 per cent surcharge appearing out of nowhere. It is not a penalty. It is the same Social Security and Medicare contribution an employee makes, with the employer side now payable by you because you are the employer.

The computation has three steps worth knowing. First, net earnings from self-employment are your Schedule C profit — receipts minus business expenses — multiplied by 92.35 per cent. That adjustment exists to mirror the fact that an employer deducts its half of payroll tax as a business expense. Second, apply 12.4 per cent for Social Security on those net earnings up to the 2026 wage base of $184,500, and 2.9 per cent for Medicare with no upper limit. Third, deduct one half of the total against your income tax as an above-the-line adjustment.

A worked example clarifies the size of it. A freelance designer with $90,000 of profit computes net earnings of $83,115. Social Security at 12.4 per cent is $10,306 and Medicare at 2.9 per cent is $2,410, a combined self-employment tax of $12,716. Half of that, $6,358, comes off income before income tax is calculated. The income tax then runs on the remaining figure less the standard deduction. Total federal liability lands far above what a naive glance at the bracket table suggests.

High earners face one more layer. The additional Medicare tax of 0.9 per cent applies to combined wages and self-employment earnings above $200,000 for single filers, $250,000 for joint filers and $125,000 for married filing separately. It is not matched by an employer portion and there is no wage base ceiling.

Because nobody is withholding for you, quarterly estimated payments are mandatory in practice. Compute your expected annual tax, divide by four, and pay by 15 April, 15 June, 15 September and 15 January. The safe-harbour rules protect you from penalties if you pay at least 90 per cent of the current year's tax or 100 per cent of the prior year's tax — 110 per cent if your prior-year AGI was above $150,000. Using last year's figure is the simplest safe harbour for anyone with volatile income.

Reducing self-employment tax legitimately is harder than reducing income tax, because business deductions reduce both while retirement contributions reduce only income tax. That makes every genuine business expense doubly valuable: home office, mileage, equipment, software, professional development, insurance, and the business proportion of your phone and internet. Keep a separate business bank account and card so the boundary is defensible if questioned.

Once profits are consistently high, an S corporation election becomes worth modelling. The owner takes a reasonable salary subject to payroll tax and receives the remaining profit as a distribution that is not. The saving can be real, but so are the costs: payroll processing, a separate corporate return, state franchise fees, and the risk that an unreasonably low salary is challenged. Most advisers see the crossover somewhere above $80,000 to $100,000 of stable profit.

The habit that prevents every self-employment tax crisis is simple: move 25 to 30 per cent of every payment received into a separate tax account the day it arrives, and pay the quarterly instalments from there. Freelancers who treat gross receipts as available income are the ones who end up negotiating instalment agreements in April.