self employment tax calculator
Estimate your 2025 Schedule SE with precision. This calculator models Social Security (12.4% up to the wage base), Medicare (2.9% on all net earnings), and the Additional Medicare tax (0.9%) using your filing status and W-2 wages to coordinate limits. Built for freelancers, contractors, and small business owners who need audit-friendly transparency.
Calculator inputs
Sets Social Security wage base for SE tax.
Affects the Additional Medicare 0.9% threshold.
Applies above filing-status threshold based on combined wages and SE net earnings.
Results
Total SE tax
$0.00
Social Security (12.4%)
$0.00
Medicare (2.9%)
$0.00
Additional Medicare (0.9%)
$0.00
1/2 SE tax deduction
$0.00
Details (tax base and thresholds)
Data source and methodology
- SSA Contribution & Benefit Base (2024–2026) — Social Security wage base (2025: $176,100). SSA official table. All computations respect this cap. “All calculations strictly follow the formulas and data provided by this source.”
- IRS Topic No. 554 & Schedule SE Instructions — 92.35% net earnings factor; 15.3% rate (12.4% + 2.9%). Topic 554, About Schedule SE, and current Instructions.
- IRS Topic No. 560 & Q&A — Additional Medicare tax 0.9% thresholds ($250k MFJ, $125k MFS, $200k others) and coordination with spouse wages. Topic 560 and Q&A.
The formula explained
Net earnings (Schedule SE base): \\( NE = 0.9235 \\times P \\) where \\(P\\) is net profit from self-employment.
Social Security tax (12.4% to wage base): \\[ SS = 0.124 \\times \\min\\big( NE, \\max(0, WB - W2_{SS}) \\big) \\]
Medicare tax (2.9% on all net earnings): \\[ MED = 0.029 \\times NE \\]
Additional Medicare (0.9% over threshold): \\[ AM = 0.009 \\times \\max\\big( 0, (W2_{Med} + NE) - T_{fs} \\big) \\] where \\(T_{fs}\\) is the filing-status threshold.
Total SE tax: \\( SET = SS + MED + AM \\). Half SE tax deduction: \\( D = \\tfrac{1}{2} (SS + MED) \\) (excludes \\(AM\\), which is not deductible).
Glossary of variables
- P: Net profit from self-employment (Schedule C line 31).
- NE: Net earnings for SE tax (= 92.35% of net profit).
- WB: Social Security wage base (2025: $176,100; 2024: $168,600).
- W2SS: W-2 Social Security wages (Box 3) — reduces SS cap available for SE income.
- W2Med: W-2 Medicare wages (Box 5) — used for Additional Medicare threshold coordination.
- Tfs: Filing-status threshold for Additional Medicare (MFJ $250k; MFS $125k; others $200k).
How it works: A step-by-step example
Example inputs
- Tax year: 2025 (WB = $176,100)
- Filing status: Single
- Net profit P: $120,000
- W-2 Social Security wages: $0; W-2 Medicare wages: $0
Computation
- \\( NE = 0.9235 \\times 120{,}000 = 110{,}820 \\).
- Social Security base remaining = \\(176{,}100 - 0 = 176{,}100\\). SS taxable = \\(\\min(110{,}820, 176{,}100)=110{,}820\\). \\( SS=0.124\\times110{,}820=13{,}742.\\overline{\\ } \\)
- Medicare = \\(0.029\\times110{,}820=3{,}213.78\\).
- Additional Medicare threshold (Single) = $200,000; combined base = \\(0 + 110{,}820=110{,}820 < 200{,}000\\Rightarrow AM=0\\).
- Total SE tax \\(SET = 13{,}742.\\overline{\\ } + 3{,}213.78 = 16{,}956.\\overline{\\ }\\).
- Half SE tax deduction \\(D = (SS+MED)/2 \\approx 8{,}478.\\overline{\\ }\\).
Frequently asked questions
Who must pay self-employment tax?
Generally, anyone with net earnings from self-employment of $400 or more must file Schedule SE and pay SE tax.
Does the 92.35% factor always apply?
Yes, it’s the standard adjustment on Schedule SE to approximate the “employee-equivalent” share of FICA.
How do W-2 wages affect my SE Social Security tax?
Your W-2 Social Security wages reduce the remaining wage base available for SE income. Only the combined amount up to the wage base is subject to the 12.4% portion.
Is the Additional Medicare 0.9% part of Schedule SE?
No. It’s computed on Form 8959 but depends on your combined Medicare wages and SE net earnings. This tool estimates it for planning.
Is Additional Medicare deductible?
No. Only one-half of the regular SE tax (Social Security + Medicare) is deductible for income-tax purposes.
Can health insurance premiums reduce SE tax?
They can reduce income tax (as an above-the-line deduction), but they don’t reduce the SE tax base unless they lower your net profit.
Tool developed by Ugo Candido. Content verified by CalcDomain Editorial Board.
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