Self-Employment Tax Calculator: Federal and State Combined for 2026

The Federal SE Tax Mechanics Every Self-Employed Worker Must Know

Self-employment tax is not income tax. It is the self-employed person's version of FICA, covering both the employee and employer share of Social Security and Medicare. For 2026, the IRS applies 12.4% for Social Security on net self-employment earnings up to $176,100. It applies a separate 2.9% for Medicare with no earnings cap. The combined rate is 15.3% up to the Social Security wage base, then 2.9% on every dollar above it.

The calculation starts with net self-employment income, which is gross self-employment revenue minus ordinary and necessary business expenses. You then multiply net SE income by 0.9235. That factor accounts for the fact that W-2 employees pay their half of FICA on pre-employer-share wages. The IRS effectively lets self-employed filers reduce their taxable SE base by the equivalent of the employer share before applying the rate.

The formula in plain text:

Net SE Income x 0.9235 = SE Tax Base

SE Tax Base x 0.153 (up to $176,100) = SE Tax Owed

You then deduct exactly half of that SE tax figure from your gross income on Schedule 1 of IRS Form 1040. That deduction reduces your adjusted gross income for federal income tax purposes, but it does not reduce your SE tax itself.

The State Layer: Where the Real Surprise Hits

State income taxes apply to self-employment income independently of federal SE tax. States do not levy their own SE tax in the FICA sense, but they do tax net self-employment income as ordinary income. That layer is where most self-employed workers underestimate their total obligation.

Nine states have no individual income tax as of 2026: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, and Wyoming. Every other state applies rates ranging from a flat 3.07% in Pennsylvania to a graduated top rate of 13.3% in California. Those rates stack on top of your federal income tax bracket, which for a self-employed filer in the 22% federal bracket means a combined marginal income tax rate of 35.3% in California before federal SE tax enters the picture.

The total effective burden on an additional dollar of self-employment income in California for a filer in that bracket: 15.3% SE tax, minus the small AGI benefit from the SE deduction, plus 22% federal income tax, plus 9.3% to 13.3% California state income tax. The combined marginal rate on new income routinely lands between 46% and 52% for high earners in that state.

Worked Example 1: Freelance Designer in Texas, $85,000 Net Income

A graphic designer in Austin nets $85,000 after business expenses in 2026. Texas has no state income tax.

SE Tax Base: $85,000 x 0.9235 = $78,498

SE Tax Owed: $78,498 x 0.153 = $12,010

Deductible Half: $12,010 / 2 = $6,005

Federal AGI After SE Deduction: $85,000 minus $6,005 = $78,995

Assuming standard deduction of $15,000 for a single filer, federal taxable income is $63,995. At 2026 rates, federal income tax on that amount is approximately $9,559.

Total federal burden: $12,010 SE tax plus $9,559 income tax = $21,569.

State burden: $0.

Total 2026 liability: $21,569 on $85,000 net, an effective combined rate of 25.4%.

Worked Example 2: Independent Consultant in California, $145,000 Net Income

A management consultant in San Francisco nets $145,000 after business deductions in 2026.

SE Tax Base: $145,000 x 0.9235 = $133,908

SE Tax Owed: $133,908 x 0.153 = $20,488

Deductible Half: $20,488 / 2 = $10,244

Federal AGI After SE Deduction: $145,000 minus $10,244 = $134,756

Assuming standard deduction of $15,000, federal taxable income is $119,756. Federal income tax at 2026 brackets is approximately $22,341 for a single filer.

Federal burden: $20,488 plus $22,341 = $42,829.

California state income tax on $134,756 AGI (after the federal SE deduction, which California also allows): approximately $13,176 at California's graduated rates, which reach 9.3% on income over $68,350.

Total 2026 liability: $42,829 plus $13,176 = $55,005 on $145,000 net. Effective combined rate: 37.9%.

That $13,176 state bill is the figure most self-employed California residents fail to prepay in quarterly estimated payments, triggering IRS Form 2210 underpayment penalties on the federal side and California FTB penalties on the state side.

Quarterly Estimated Payments: Deadlines and Safe Harbor Thresholds

Self-employed filers must prepay both federal and state tax in quarterly installments. For 2026, the IRS deadlines are April 15, June 16, September 15, and January 15, 2027. California Franchise Tax Board mirrors the April and June dates but moves the third installment to September 15 and eliminates the January installment, requiring full payment by September 15 for Q3 and Q4 combined.

The federal safe harbor rule requires paying the lesser of 100% of your 2025 total tax liability or 90% of your projected 2026 liability. For filers whose 2025 adjusted gross income exceeded $150,000, the threshold rises to 110% of the prior year's liability. California applies the same 110% rule at the same AGI threshold.

Missing these thresholds by even one quarter generates a penalty calculated at the federal short-term rate plus 3 percentage points, applied daily to the underpaid amount. On a $20,000 shortfall, that penalty can reach $400 to $600 per quarter.

The Additional Medicare Tax: High Earners Pay More

Self-employed filers with net earnings above $200,000 (single) or $250,000 (married filing jointly) owe an Additional Medicare Tax of 0.9% on all net self-employment income above those thresholds. This does not appear in the SE tax schedule itself. It shows up on IRS Form 8959 and flows to Form 1040. It is not deductible.

A single filer netting $280,000 from self-employment pays 0.9% on $80,000, adding $720 to the total liability beyond the standard SE calculation.

Run the Full Combined Calculation Before Your Next Quarterly Payment

The only accurate way to set quarterly estimated payment amounts is to model your full-year federal and state obligations together, not separately. Federal SE tax, federal income tax, state income tax, and the Additional Medicare Tax all draw from the same pool of net earnings. Calculating them in isolation produces payment estimates that are too low.

The CalcMoney income tax calculator handles all four components simultaneously. Enter your projected net self-employment income, your filing status, and your state. The tool returns your federal SE tax, your federal income tax by bracket, your state income tax, and a recommended quarterly payment for the period you select.

Calculate your 2026 combined self-employment tax now →

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Results are estimates for informational purposes only. Consult a licensed financial professional before making financial decisions.