Self Employed Tax Calculator
Calculate your income tax, Class 2 and Class 4 National Insurance. See detailed breakdowns and explore expense scenarios to minimize your tax bill.
Calculate Your Tax
£
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Profit: £42,000
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💡 Tax Optimization
Better when expenses < £1,000
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Your Results
Your Take-Home
£0
Taxable Profit
£0
Income Tax
£0
Class 2 NI
£0
Class 4 NI
£0
Total Tax & NI
£0
Effective rate: 0%
📊 Detailed Tax Breakdown
See exactly how your tax is calculated
| Component | Calculation | Rate | Amount |
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📚 Self-Employment Tax Jargon Buster
Click on any term to learn more
Class 2 NI
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Flat weekly amount (£3.45/week = £179.40/year for 2025/26) paid if your profits exceed £6,725. Gives you State Pension credits and access to certain benefits.
Class 4 NI
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Percentage-based NI on profits: 9% on £12,570-£50,270, then 2% above £50,270. Unlike Class 2, this doesn't give additional benefit rights.
Taxable Profit
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Turnover minus allowable expenses and deductions. This is what you pay tax on, not your total income. Lower taxable profit = lower tax.
Self Assessment
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Annual tax return you must file if self-employed. Deadline: 31 January for online filing. Late filing = £100 minimum penalty, plus daily penalties after 3 months.
Payment on Account
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HMRC makes you pay tax in advance for next year. You pay 50% by 31 Jan and 50% by 31 July. Budget for 1.5x your tax bill in January!
Trading Allowance
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£1,000 tax-free allowance. If turnover under £1,000, it's all tax-free. If over, choose £1,000 allowance OR actual expenses — whichever is better.
Allowable Expenses
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Costs "wholly and exclusively" for business: office supplies, travel, equipment, professional fees, insurance. Not allowable: personal costs, entertainment, clothes (unless uniform).
Mileage Allowance
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Claim business miles at HMRC rates: 45p per mile (first 10,000), then 25p. Motorcycles: 24p. Bicycles: 20p. Keep detailed mileage logs!
How This Calculator Works
Our self-employed tax calculator provides accurate estimates for 2025/26:
- Income Tax: Calculated on profit above £12,570 at 20%, 40%, or 45%
- Class 2 NI: £3.45/week (£179.40/year) if profit over £6,725
- Class 4 NI: 9% on profits £12,570-£50,270, then 2% above
- Visual Breakdowns: Charts showing where your money goes
- Tax Optimization: See impact of expenses and deductions
⚠️ Disclaimer: This calculator provides estimates based on 2025/26 tax year rates. Your actual tax may vary based on other income, allowances, and personal circumstances. This tool is for guidance only and does not constitute financial advice. Always verify calculations with HMRC or a qualified accountant.