How do I calculate my self-employment tax?

Calculate net profit after business expenses, multiply by 0.9235 to get net earnings subject to self-employment tax, then apply the combined self-employment tax rate to estimate the tax owed.

Can I reduce the amount of self-employment tax I owe?

You can reduce taxable income through legitimate business expenses, retirement contributions, and allowable deductions like health insurance premiums, and by planning quarterly payments to avoid penalties.

Self-Employment Tax: How Much Will You Owe?

An easy-to-follow, step-by-step to calculating and controlling your self-employment tax.

If, like me, you run your own business or have an independent contract role, self-employment tax is something you need to know about. While employees can count on an employer to withhold payroll taxes, self-employed people have to pay the employee and employer portions of Social Security and Medicare tax on their own. Understanding how to estimate what you’ll owe, and when to pay, helps ensure that you don’t get caught off guard by a larger-than-expected balance due in April.

What self-employment tax covers

Self-employment tax is a system used to help fund social security and medicare contributions of those that work for themselves. Those taxes go to pay retirement, disability and Medicare benefits for qualifying recipients. It is in addition to income tax and is levied on net earnings from self-employment after allowable business expenses.

Step-by-step se tax calculation

Calculate your net profit: Begin with gross receipts from your business, then subtract ordinary and necessary business expenses to calculate your net profit. Maintain good records of income and receipts for deductions.
Determine net income subject to self-employment tax: Not all of your net profit is subject to the total amount of the self-employment tax. A common bear-down is to decrease net income slightly (to account for the employer portion of some payroll taxes). Multiply your net profit by 0.9235 to find the net earnings subject to self-employment taxes.
Multiply by the self-employment tax rate: Use the aggregate self-employment tax rate and multiply that percentage by the net return from step 2. This is the rate for Social Security and Medicare combined. Multiply your net profits by the entire self-employment tax rate to determine the tax that is owed.
Deductible portion: You can deduct half of your self-employment tax on your income tax return. This lowers your taxable income for purposes of the income tax, but it is does not count against the actual self employment tax due.
Pay quarterly estimated taxes: If you think you will owe a certain amount when filing, pay quarterly estimated tax payments to avoid interest and penalties. Use your estimated net income to compute each quarter’s payment and make changes as your income fluctuates.

Example calculation

For example, let’s say you earn $100,000 in gross freelance income from your side-business over the year, and have $20,000 of allowable business expenses for that same period. Your net profit is $80,000.

Net income subject to self employment tax = $80,000 × 0.9235 = $73,880.
If the self-employment tax rate is 15.3 percent (including both Social Security and Medicare), then Under this formula: Self-Employment Tax = $73,880 × 0.153 = $11,305.64.
Half of that ($5,652.82) can be taken as an adjustment to income on your personal tax return, putting a smaller number into the AGI sum for income tax purposes.
These amounts are representative and demonstrate of the logic of the calculation: net profit → adjusted net income → tax at combined rate → deduction for 1/2 tax.

Practical considerations and edge cases

Income limits for portions of the tax: Certain pieces of the total self-employment tax apply only up to specified income levels and others are applied against all earned-income amounts. With a very high income, some pieces may stop at a cap, while the Medicare parts have no cap. Consider this when forecasting liability.
Additional Medicare taxes: High earners in certain situations will be required to pay additional Medicare taxes above and beyond the normal rate. If you anticipate high earnings, see instructions for the additional Medicare tax for high earners.
Multiple sources of income: If you earn wages and also have self-employment income, the interplay between payroll withholding and self-employment tax can be confusing. When you work as someone else’s employee, some of your Social Security and Medicare liability is paid through payroll taxes; however, you’ll still need to do the math on self-employment taxes and coordinate payments to guard against underpayment.

How To Control And Reduce Liability

Maximize your real business expenses: The more you can claim as legitimate business expenses, the smaller your true profit and therefore the lower your self-employment tax base. Keep an accurate record of expenses that are reasonable and essential to your business activity.
Leverage retirement and tax-advantaged accounts: Contributing to retirement vehicles that cater specifically to the self-employed can help lower taxable income while creating long-term savings. Although these contributions don’t always reduce the self-employment tax base directly, they usually do decrease taxable income (income taxes) and offer other advantages.
Health insurance premiums: Self-employed individuals can often deduct premiums for health insurance covering themselves and their families as an adjustment to income, which lowers taxable income.
Business structure matters: The legal structure you choose for your business can have an impact on tax treatment. Some structures permit tax strategies to be used that alter the way payroll taxes are treated. This type of structural change should be analyzed with the advice of a tax professional to ensure compliance and assess administrative costs versus benefits.

Recordkeeping and compliance tips

Keep good records: Keep accurate books on your small business regarding income and expense. Save receipts, invoices and bank statements, as well as logs of business use in case you’re ever audited.
Save for taxes: A general rule of thumb is to save a certain percentage of net gains — at least the amount you’ll owe in self-employment tax, plus an educated guess at income tax. For many self-employed workers, 25–30% or more should be put aside depending on the tax bracket they wind up in and what their state obligations are.
Pay quarterly estimated payments: Guess your tax due on projected net income and make payments every quarter to avoid an underpayment penalty. If your income is subject to wild swings throughout the year, make sure you’re adjusting payments.

Final thoughts

Knowing how self-employment tax is calculated can help you manage your cash flow and work out a tax strategy. Begin with a precise figure for net income, apply an adjustment representing net earnings subject to tax, and then calculate what you’ll owe based on the joint tax rate. And be sure to take and hold on to eligible deductions, save for quarterly payments and support records. Careful tax planning can help reduce surprises come filing time and maintain the health of your business finances.