Employed and Self-Employed Tax Calculator
If you have a job and run your own business on the side, your tax isn’t worked out separately for each. HMRC adds your employment income and self-employment profit together to work out your tax band. This calculator gives you a combined picture in one place.
How to Use This Calculator
- Enter your employed income — your gross salary before tax (as shown on your payslip or P60).
- Enter your self-employed profit — your self-employment income minus allowable business expenses.
- Get your results: total Income Tax across both incomes, Class 1 NI from your employment, Class 4 NI from your self-employment, and your combined take-home amount.
How Combined Employed and Self-Employed Tax Works
1. Income Tax is based on your total income
Your employment income and self-employment profit are added together first. Your Personal Allowance and tax bands are then applied to that combined total — not to each income separately.
Band | Total Taxable Income | Rate |
Personal Allowance | Up to £12,570 | 0% |
Basic rate | £12,571 – £50,270 | 20% |
Higher rate | £50,271 – £125,140 | 40% |
Additional rate | Over £125,140 | 45% |
Because the two incomes are combined, your self-employed profit often gets taxed at your highest marginal rate — so if your job already uses up your basic rate band, your side income may be taxed at 40% straight away.
2. You pay two different types of National Insurance
Unlike Income Tax, National Insurance is calculated separately for each type of income:
Class 1 (from employment) — deducted automatically through PAYE by your employer:
Band | Weekly/Annual Earnings | Rate |
Below Primary Threshold | Up to £12,570/year | 0% |
Main rate | £12,570 – £50,270/year | 8% |
Above Upper Earnings Limit | Over £50,270/year | 2% |
Class 4 (from self-employment) — paid through Self Assessment:
Band | Annual Profit | Rate |
Below threshold | Up to £12,570 | 0% |
Main rate | £12,570 – £50,270 | 6% |
Above threshold | Over £50,270 | 2% |
There’s an “annual maximum” rule that can cap your combined NI if you earn close to or above the Upper Earnings Limit through both jobs — an accountant can check whether this applies to you, since it can mean a refund.
Worked Example
Employed salary: £35,000 | Self-employed profit: £15,000 | Total income: £50,000
Income Tax (on combined £50,000):
- First £12,570: tax-free
- Remaining £37,430 at 20%: £7,486
Class 1 NI (on £35,000 salary, via PAYE):
- £12,570–£35,000 (£22,430) at 8%: £1,794.40
Class 4 NI (on £15,000 self-employed profit):
- All £15,000 falls in the £12,570–£50,270 band
- £15,000 – £12,570 = £2,430 at 6%: £145.80
Total tax and NI: approximately £9,426.20
Estimated combined take-home: approximately £40,573.80
(Rounded estimate — doesn’t account for pension contributions, student loans, or other reliefs.)
Do I Need to Register for Self Assessment?
Yes — if you have any self-employment income alongside your job, you must register for Self Assessment and file a tax return, even if your side income is small. As of 2026/27, HMRC generally expects you to register once your gross self-employment income exceeds £1,000 in a tax year (the “trading allowance”).
Why Use This Calculator?
- Combines both income sources correctly, the way HMRC actually taxes them
- Shows Class 1 and Class 4 NI separately
- Up to date with 2026/27 rates
- Free, instant, no sign-up needed
- Built by qualified London accountants
Frequently Asked Questions
Does my employer's PAYE tax code account for my self-employed income?
No, not usually. Your employer only taxes your salary. Your self-employment profit is reported and taxed separately through Self Assessment, though HMRC may adjust your tax code later to collect tax on it in advance.
Will I pay National Insurance twice?
You pay Class 1 on your salary and Class 4 on your profits, but there’s a cap on the total NI you’re required to pay (the “annual maximum”). If your combined earnings are high, you may be able to claim a partial refund.
Do I need to register as self-employed if I already have a job?
Yes, if your self-employment income is more than £1,000 a year, you need to register with HMRC and file a Self Assessment return.
What if I'm employed by my own limited company instead?
That’s a different situation — company directors are taxed via salary, dividends and Corporation Tax rather than as a sole trader. We have a separate [Limited Company Tax Calculator] for that.
Is this calculator accurate enough for filing?
It’s a solid planning estimate, but your actual liability depends on your full circumstances, including any reliefs or the NI annual maximum rule — best to confirm with an accountant before you file.
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