How Do Taxes Work for Self-Employed Income in the US?

How do taxes work for self-employed income in the US? Nobody withholds your taxes when you’re your own boss — which feels like a raise until April arrives with a bill that makes you queasy. Self-employment tax is the number-one financial shock for new freelancers, and it’s entirely preventable with a little knowledge.

I learned this the hard way in year one. Here’s the complete picture so you don’t have to.

How Do Taxes Work for Self-Employed Income? The Two Taxes

You pay two layers. Income tax: same as everyone else, on your net profit (revenue minus deductible expenses), at your marginal bracket. Self-employment tax: 15.3% on 92.35% of net profit — that’s 12.4% Social Security (up to the annual cap, ~$168,600) plus 2.9% Medicare (no cap). This replaces the 7.65% FICA your employer used to pay plus the 7.65% they paid on your behalf — being your own boss means both halves.

The math that shocks people: $60,000 net profit means roughly $8,478 in SE tax plus income tax on top. Effective total tax rates of 25–30% on profit are normal. It’s not unfair — employees pay the same via withholding, they just never see it. But seeing the full number at once is why quarterly payments (below) are non-negotiable. The IRS self-employed center at the IRS small business center is the authoritative reference.

Quarterly Estimated Payments (Don’t Skip These)

Because nothing is withheld, you pay in four quarterly installments (April, June, September, January). Miss them and you’ll owe underpayment penalties plus a giant April bill. The safe harbor: pay 100% of last year’s total tax (110% if you earned over $150k) across the four quarters and you won’t be penalized even if you earn more this year.

New freelancers with no ‘last year’ should just pay 25–30% of each quarter’s profit as they go — the pay-as-you-earn habit from our Is it worth opening a business bank account for a side hustle banking guide automates this beautifully. Use IRS Direct Pay (free) or EFTPS; it takes five minutes per quarter. The penalty for skipping isn’t huge, but the April cash-flow crisis it causes absolutely is.

Deductions: The Legal Ways to Shrink the Bill

Every legitimate business expense reduces taxable profit: home office (simplified: $5/sq ft up to 300 sq ft), health insurance premiums (if self-employed), retirement contributions (SEP-IRA or Solo 401k — the biggest deduction most freelancers miss), business mileage ($0.67/mile for 2024; check current rate), software, phone/internet portion, professional development, and business meals (50%).

The retirement-contribution deduction deserves emphasis: a Solo 401k lets you shelter up to ~$69,000/year (2024 limits; check current), crushing your tax bill while building wealth. Most freelancers leave this money on the table for years. Track everything in real accounting software (see What is the best free accounting software for small businesses) — deductions you can’t document are deductions you can’t take, and the IRS can ask.

Self-employment tax survival checklist:

• Budget 25–30% of profit for total taxes — it’s not optional, it’s arithmetic.
• Pay quarterly estimates; use the safe harbor (100%/110% of last year’s tax).
• Track every deductible expense in real software from day one.
• Open a Solo 401k or SEP-IRA — the most-missed big deduction.
• Get a CPA once you’re consistently profitable; it pays for itself.

Mistakes That Cost Real Money

Classic errors: not making quarterly payments (penalties + April shock), mixing personal and business money (lost deductions, audit risk), forgetting the home-office and retirement deductions (thousands left on the table), misclassifying employees as contractors (the IRS cares deeply about this — see What is the difference between a 1099 and a W-2 worker), and trying to deduct everything aggressively (the ‘write-off’ myth — a deduction saves you 25 cents per dollar, it’s not free money).

When to hire help: once you’re consistently profitable, a CPA ($300–$800/year for a freelancer return) usually pays for itself in found deductions and avoided mistakes. DIY with software is fine for simple situations; get professional help when you hire, incorporate, or cross ~$100k. Taxes are a game with rules — learn them once and they pay you back every year.

The Bottom Line

How Do Taxes Work for Self-Employed Income in the US? What Most People Get Wrong

What most new freelancers get wrong: thinking quarterly payments are optional because ‘I’ll settle up in April.’ They’re not optional — the IRS charges underpayment penalties, and worse, the April bill arrives as a five-figure shock that wrecks cash flow. The safe harbor rule (pay 100% of last year’s tax across four quarters) makes compliance mechanical: divide last year’s total tax by four, pay that each quarter, done. No estimating, no stress, no penalties.

Second mistake: deducting without documenting. The home office, the mileage, the meals — all legitimate, all worthless without contemporaneous records. The IRS doesn’t require perfection; it requires credibility: a mileage log, receipts photographed monthly, a simple spreadsheet. And the biggest miss of all: retirement contributions. A Solo 401k contribution is the rare triple win — reduces today’s taxes, builds wealth, and costs nothing but the paperwork. Most freelancers leave thousands on this table for years.

Pay quarterly estimates through IRS Direct Pay and save every confirmation — it’s free, fast, and creates a paper trail that ends all disputes about whether you paid. Set calendar reminders for the four deadlines (April, June, September, January) with a one-week advance warning, and make the payment a non-negotiable appointment like any client meeting. The freelancers who get penalized aren’t usually evading; they’re procrastinating. The system is simple; the discipline is the whole game.

Self-employed taxes mean paying both income tax and 15.3% self-employment tax on your profit, in quarterly installments, with no withholding to save you. Budget 25–30%, pay quarterly via the safe harbor, deduct everything legitimate (especially retirement contributions), and get a CPA when it matters. It’s the least fun part of freelancing, but it’s just a system — learn it once, automate it, move on.

Self-employment tax is just a system: budget 25–30%, pay quarterly via safe harbor, document deductions as you go, fund the Solo 401k. Learn it once, automate it, and it fades into the background. The freelancers who struggle with taxes aren’t worse at business — they just never built the system. Build it now.