When you have a W-2 job, your employer pays half of your Social Security and Medicare contributions and you pay the other half. You see the 7.65% on your pay stub labeled FICA.
When you're self-employed, you're both halves. That's 15.3% on top of regular income tax. It's the surprise that turns "I made $40,000 driving last year" into "wait, why do I owe $10,000?"
The math
Self-employment tax is calculated on Schedule SE and breaks down like this:
- 12.4% — Social Security (on earnings up to roughly $168,600 in 2026)
- 2.9% — Medicare (no income cap)
- Total: 15.3% on net self-employment income
"Net self-employment income" means gross income minus business expenses (mileage, phone, supplies). You only pay SE tax on what's left after deductions.
One small mercy: you get to deduct half of the SE tax — the "employer half" — from your income before calculating income tax. So the 15.3% doesn't compound with income tax brackets quite as hard as it looks.
Who owes it
Anyone with $400 or more in net self-employment earnings in a year. That threshold is low and hasn't been updated since the 1950s. Practically everyone in the gig economy hits it.
Self-employment income includes:
- Rideshare and delivery (Uber, Lyft, DoorDash, Instacart)
- Independent contractor hair and beauty work (booth-rent)
- Independent contractor massage and personal training
- Freelance bartending and catering gigs
- Any 1099-NEC or 1099-K income above $400
A worked example
Maria drove DoorDash and Uber Eats. She grossed $38,000 last year. After mileage (14,000 miles × 70¢ = $9,800), phone (60% of $1,200 plan = $720), and supplies ($200), her net self-employment income is $27,280.
SE tax: $27,280 × 0.9235 (the IRS factor for SE tax calculation) × 15.3% = $3,855
She also owes federal income tax on her net income, minus the standard deduction and half her SE tax. After all that, her total tax bill is roughly $5,700 on $38,000 grossed.
That's about 15% all-in — much less than people fear, but only because the mileage deduction did heavy lifting. Without it, she'd be looking at $10,000+.
How to soften the hit
Track every deductible expense. Mileage is the big one. Phone, supplies, percentage of home internet if you use it for app coordination, accounting software, even the cost of dispatching apps and tax software — all deductible.
Pay quarterly. See our quarterly guide. You don't escape the tax this way, but you avoid the underpayment penalty.
Open a SEP-IRA or solo 401(k). Self-employed workers get retirement vehicles W-2 employees don't. A SEP-IRA contribution up to 25% of net self-employment income reduces taxable income directly and grows tax-deferred. For a driver making $30K net, that could be $7,500 of pre-tax savings that also drops the tax bill by $1,200+.
Consider an S-corp election if your net is consistently above ~$60K. This is a real CPA conversation, not a back-of-envelope move. But the SE tax savings can be substantial if your business is profitable enough to justify the additional filing complexity.
What you cannot do
You cannot opt out of Social Security on a "I'll never need it" theory. You cannot skip the tax and just pay income tax on your 1099 income — the IRS will catch this when your 1040 doesn't have a matching Schedule SE. You cannot pay yourself "wages" to avoid SE tax unless you've formally elected S-corp status.
What you can do is be relentless about deductions and pay quarterly. Both shave the bite.