Add up your net earnings from self-employment
Use Schedule C, Schedule F, or your business records to find net profit
Multiply net earnings by 92.35% to get the amount subject to self-employment tax
Apply the self-employment tax rate of 15.3%
Split the tax into 12.4% for Social Security and 2.9% for Medicare
Stop applying the 12.4% Social Security portion once your earnings exceed the annual Social Security wage base
Add the 0.9% Additional Medicare Tax if your total wages and self-employment income exceed the IRS threshold
Subtract any allowable deductions related to self-employment tax, if applicable
Use IRS Schedule SE to calculate the exact tax amount
Include the self-employment tax on your federal tax return
Make estimated tax payments during the year if required