How Self Employment Tax Is Calculated

Federal self-employment tax starts with net earnings from self-employment. IRS instructions for Schedule SE apply a net earnings factor—commonly 92.35% of net profit—to approximate the amount subject to Social Security and Medicare taxes.

The Social Security portion uses a fixed rate on net self-employment earnings up to the annual wage base for the tax year. Above that base, Social Security tax generally does not apply to additional earnings, though Medicare tax continues.

Medicare tax applies at a separate rate on all net self-employment earnings (subject to Schedule SE rules). High earners may also be subject to Additional Medicare Tax on wages and self-employment income above IRS thresholds, which is outside the scope of basic self-employment tax estimates.

Taxpayers can generally deduct the employer-equivalent portion of self-employment tax when figuring adjusted gross income. Planning tools may show gross self-employment tax and net federal impact separately.

TaxChecker's Self-Employed Tax Calculator and 1099 Tax Calculator apply the same documented formulas used on calculator pages and worked examples. Results are simplified federal estimates for planning—not tax returns.

For bracket context after deductions, see the Federal Tax Brackets 2025 Explained article and the Tax Brackets 2025 resource table sourced from IRS Revenue Procedure 2024-40.