This self-employed tax calculator does it all in one place. Enter your salary, your self-employed income, and any expenses and get an instant breakdown of exactly what you owe to HMRC, what your employer handles, and what lands in your pocket.
Tax Breakdown Your Results
Once you’ve entered your figures, your results will show everything in one clean summary:
- Total income (salary + self-employed profit)
- Income Tax split across the 20%, 40% and 45% bands
- National Insurance Class 1 (via PAYE) and Class 4 (via Self Assessment)
- Tax already paid what your employer deducts automatically each month
- Remaining tax to pay what you owe via your Self Assessment return
- Take-home income yearly and monthly
💡 Unlike most calculators that show PAYE and self-employment tax separately, this self-employed tax calculator combines both into one complete picture so you can see your actual take-home without having to do any extra maths.
How Your Tax Is Calculated
When you’re both employed and self-employed, HMRC treats all your income together but the way it’s collected is split between two systems.
Step 1 Work out your self-employed profit
Your self-employed income isn’t all taxable. You can deduct allowable business expenses (travel, equipment, subscriptions) to arrive at your net profit. If you don’t have expenses to claim, the £1,000 Trading Allowance is applied automatically meaning the first £1,000 of your self-employed income is completely tax-free.
Step 2 Combine your income and apply the Personal Allowance
Your salary and self-employed profit are added together. The first £12,570 is covered by your Personal Allowance and is tax-free. If your total income exceeds £100,000, the Personal Allowance tapers down disappearing completely at £125,140.
Step 3 Apply income tax bands
Your salary fills the income tax bands first. Self-employed income then uses whatever band space remains. This matters because if your salary already reaches the 40% threshold, all your self-employed income is taxed at 40% not 20%.
Step 4 Calculate National Insurance
Your employer deducts Class 1 employee NIC from your salary (8% between £12,570 and £50,270, then 2% above). On top of that, you pay Class 4 NIC on your self-employed profit through Self Assessment 6% up to £50,270 and 2% above. Class 2 NIC was abolished from April 2024.
What Affects Your Tax Liability
- Business expenses the more legitimate expenses you claim, the lower your taxable profit. Keep receipts for anything that’s wholly and exclusively for your business.
- The £1,000 Trading Allowance if your expenses are under £1,000, it’s usually simpler to claim the flat allowance instead. You can’t claim both.
- Your tax code an incorrect PAYE tax code can mean you’re overpaying or underpaying tax on your salary. Check yours on your payslip or via HMRC online.
- NI classes employed workers pay Class 1. Self-employed workers pay Class 4. If you’re both, you pay both but this calculator accounts for all of them.
- Pension contributions payments into a workplace or personal pension reduce your taxable income, which can keep you within a lower tax band.
Tax Rates & Thresholds 2025/26
| Band | Taxable Income | Rate | NI Rate (Class 4) |
|---|---|---|---|
| Personal Allowance | £0 £12,570 | 0% | 0% |
| Basic Rate | £12,571 £50,270 | 20% | 6% |
| Higher Rate | £50,271 £125,140 | 40% | 2% |
| Additional Rate | Above £125,140 | 45% | 2% |
Employee NIC: 8% on earnings between £12,570£50,270, then 2% above. The Personal Allowance tapers from £100,000 and disappears at £125,140.
Example Calculation Side Hustle Scenario
Say you earn £40,000 as an employee and £10,000 from freelance work, with £2,000 in business expenses:
| Salary | £40,000 |
| Freelance income | £10,000 |
| Less: expenses | − £2,000 |
| Self-employed profit | £8,000 |
| Total income | £48,000 |
| Personal Allowance | − £12,570 |
| Taxable income | £35,430 |
| PAYE Income Tax (20% on £27,430 of salary) | £5,486 |
| SE Income Tax (20% on remaining £8,000) | £1,600 |
| Employee NIC (8% on £27,430) | £2,194 |
| Class 4 NIC (6% on £8,000) | £480 |
| Total tax | £9,760 |
| Take-home pay | £38,240 |
💡 Your employer handles the PAYE deductions. You pay the SE Income Tax and Class 4 NIC yourself via Self Assessment in this example, that’s £2,080 due by 31 January.
How to Pay Your Tax Self Assessment
Your employer handles all the PAYE tax and NIC on your salary automatically. But your self-employed income is your responsibility.
- Register for Self Assessment with HMRC if you haven’t already (required if SE income exceeds £1,000).
- File your tax return online by 31 January following the end of the tax year.
- Pay any tax owed by the same 31 January deadline late payment triggers interest and penalties.
- Payments on account if your Self Assessment tax bill exceeds £1,000, HMRC may ask you to make advance payments towards the following year (due 31 January and 31 July).
Frequently Asked Questions
What does it mean to be both employed and self-employed?
It means you have a PAYE job where your employer deducts tax, and you also earn money independently through freelancing, a side business, consultancy, or any trade. Both income streams are taxable, but they’re reported differently.
Do I pay more tax with a side hustle?
Not necessarily more tax as a percentage but your self-employed income is added on top of your salary, which can push some of it into a higher band. If your salary already takes you to £50,270, your entire self-employed profit is taxed at 40% rather than 20%.
What is the £1,000 Trading Allowance?
It’s a tax-free allowance for self-employed income. If your expenses are under £1,000, you can simply deduct £1,000 instead of itemising. This self-employed tax calculator applies it automatically if you leave the expenses field blank.
Do I need to register for Self Assessment?
Register for Self Assessment if your self-employed income exceeds £1,000 (Trading Allowance threshold). If between £1,000-£3,000, use HMRC’s simplified online service; over £3,000 requires full Self Assessment. Register by 5 October following the tax year end
What expenses can I claim?
You can deduct any cost that is wholly and exclusively for your business including travel (not commuting), tools and equipment, software subscriptions, professional fees, a proportion of your home if you work from there, and marketing costs.
What happens if I don’t declare my self-employed income?
HMRC can investigate and issue penalties of up to 100% of the unpaid tax, plus interest. Undisclosed income is taken seriously it’s always better to declare and pay than to risk a penalty investigation.
Can I reduce my self-employed tax bill?
Yes. Claim all allowable expenses, contribute to a pension (reduces taxable income), use the Trading Allowance if it’s better than your actual expenses, and make sure your PAYE tax code is correct. This self-employed tax calculator lets you model different expense levels to see the impact in real time.
This self-employed tax calculator provides estimates based on standard HMRC rates and thresholds for the selected tax year. It does not constitute financial or tax advice. For complex situations, speak to a qualified accountant or tax adviser.