Learn what self-employment tax covers, who pays it, how Schedule SE calculates it, and how it differs from federal and California income tax.
Self-employment tax is the federal Social Security and Medicare tax that generally applies to net earnings from self-employment. It is separate from federal income tax. A self-employed person may owe both taxes on the same business profit.
The regular self-employment tax rate combines 12.4% for Social Security and 2.9% for Medicare, totaling 15.3%. The structure resembles the Social Security and Medicare taxes imposed on employee wages. An employee and employer ordinarily split those taxes. A self-employed individual calculates both portions through Schedule SE.
The Social Security portion stops after combined wages and covered self-employment earnings reach the annual Social Security wage base. The regular Medicare portion has no comparable wage cap. Additional Medicare Tax may apply above its own threshold and is calculated separately on Form 8959.
A person generally must file Schedule SE when net earnings from self-employment are $400 or more. Self-employment income may come from a full-time business, freelance work, a gig activity, or a profitable part-time trade or business.
Receiving a Form 1099 is not the test. Income can be taxable and subject to self-employment tax even when no payer issues a form. The underlying facts control.
Partners may have self-employment earnings reported through Schedule K-1. S corporation shareholders generally do not treat corporate distributions as self-employment earnings, but shareholder-employees must receive reasonable compensation subject to payroll taxes for services performed.
For a typical Schedule C business:
The 92.35% factor reflects the employer-equivalent adjustment built into the calculation. It is not an extra receipt or an optional expense.
Assume a sole proprietor has $72,000 of gross receipts and $22,000 of deductible business expenses:
| Step | Calculation | Amount |
|---|---|---|
| Schedule C net profit | $72,000 − $22,000 | $50,000 |
| Net earnings for Schedule SE | $50,000 × 92.35% | $46,175 |
| Illustrative SE tax | $46,175 × 15.3% | $7,064.78 |
This simplified example assumes no wages, no wage-base limitation, and no special adjustments. The taxpayer may generally deduct one-half of the calculated self-employment tax as an adjustment to adjusted gross income. That deduction reduces AGI; it does not reduce the self-employment tax already calculated.
Income tax is calculated using taxable income, filing status, rates, deductions, and credits. Self-employment tax is calculated from covered net self-employment earnings. A person can owe self-employment tax even if deductions and credits reduce regular income tax to zero.
The qualified business income deduction, when available, may reduce taxable income but generally does not reduce self-employment tax. Business expenses that legitimately reduce Schedule C profit can affect both calculations.
Clients usually do not withhold tax from contractor payments. A self-employed taxpayer may need quarterly estimated payments covering expected income tax and self-employment tax. A person who also receives wages may instead increase paycheck withholding. Federal safe-harbor rules and California payment rules should be evaluated separately.
California does not impose a separate tax called "self-employment tax" that mirrors federal Schedule SE. California taxes taxable business income through its individual income-tax system and may require estimated payments. A federal adjustment connected with self-employment tax should not be assumed to receive identical state treatment without checking the current Schedule CA instructions.
Heath Income Tax can reconcile business records, calculate federal and California tax projections, and help self-employed taxpayers plan payments before filing season.
Is self-employment tax 15.3% of all my income?
No. It generally applies to covered net earnings from self-employment, subject to the Schedule SE calculation, wage-base interaction, and special rules.
Do I owe it if my business is part time?
Potentially. A genuine part-time trade or business can produce self-employment earnings when net earnings reach $400.
Does an LLC avoid self-employment tax?
Not automatically. Federal tax classification and the character of the owner's income matter.
Does California charge self-employment tax?
California does not impose a separate Schedule SE-style tax, but state income tax and estimated-payment requirements may apply.
The definitions and examples on this page are for informational purposes only and do not constitute tax advice. Tax laws change frequently and individual circumstances vary. Consult a qualified tax professional before making decisions based on this content.
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