Self-Employment Tax Calculator

Put these in the contract

Most disputes come from the basis, not the number. Writing down whether the amount is gross or net, who withholds, and when payment is due keeps reconciliation simple.

• Basis: is the figure gross revenue or net of expenses
• Payment terms: net 15, net 30, or on milestone acceptance
• Who files what: 1099-NEC thresholds and responsibilities
• Expense reimbursement: billed separately or included
• Revision scope and the rate for work beyond it
• Late-payment terms and interest if applicable

Why the calculator uses 92.35%

Self-employment tax applies to 92.35% of net earnings, not 100%. The reduction approximates the employer-share deduction that employees never see on their paycheck.

• Net profit × 0.9235 = net earnings subject to SE tax
• The 15.3% rate splits into 12.4% Social Security and 2.9% Medicare
• Only the Social Security portion stops at the annual wage base
• Medicare has no ceiling and adds 0.9% above the threshold
• W-2 wages already taxed reduce the Social Security base

Quarterly estimates and penalties

Freelancers generally pay estimated tax four times a year. Missing them can trigger an underpayment penalty even if you settle the full amount in April.

• Safe-harbor rules can be met by paying a share of last year's tax
• Income that arrives unevenly may allow the annualized method
• State estimated payments follow separate schedules
• Half of SE tax is deductible above the line on Form 1040
• Keep records of every payment confirmation

Check these before entering numbers

Confirm whether the contract amount is gross revenue or net profit. SE tax applies to net profit after business expenses, not to what the client pays you.

• Enter net profit, not gross revenue
• Subtract deductible business expenses first
• W-2 wages you already earned reduce the Social Security portion
• One quarter of the year is not a required payment schedule

SE tax is not your whole tax bill

Self-employment tax covers Social Security and Medicare only. Federal and state income tax are calculated separately on taxable income.

• Half of SE tax is deductible above the line
• The Social Security portion stops at the annual wage base
• The Medicare portion has no cap and adds 0.9% above threshold
• Quarterly estimated payments avoid underpayment penalties

Start with net profit

Enter business profit after ordinary and necessary business expenses, not total client receipts. That distinction changes the tax base.

SE earnings formula

The model uses taxable SE earnings equal to net profit multiplied by 92.35%. This is the base used for the SE-tax estimate.

Social Security portion

Social Security is estimated at 12.4% of taxable SE earnings up to the annual wage base, reduced by applicable W-2 wages already subject to Social Security.

Medicare portion

Medicare is estimated at 2.9% of taxable SE earnings. Unlike Social Security, this part is not capped by the Social Security wage base.

Additional Medicare

The model adds 0.9% above the selected threshold.

• Single or head of household: $200,000
• Married filing jointly: $250,000
• Married filing separately: $125,000

Simple example

With $50,000 of net profit and no W-2 wages, taxable SE earnings are $46,175 before the Social Security and Medicare rates are applied.

Reverse a target

The target operation estimates the net profit needed to reach a chosen amount after estimated SE tax. It does not solve for income tax or state tax.

Quarterly planning

The quarterly operation divides the annual SE-tax estimate by four. Actual estimated-tax due dates, safe harbors, and payment requirements may differ.

Scope and common mistakes

This is an SE-tax planning model, not total tax.

• Do not enter gross revenue as net profit
• Do not ignore W-2 wages
• Do not treat one-fourth as a required payment

Before relying on it

Confirm the tax year, filing status, current wage base, W-2 wages, income-tax estimate, and whether your facts require a tax professional.