As a sole trader, you pay income tax and National Insurance on your business profits. There is no separation between you and your business for tax purposes – your business profits are your personal income, and you report them to HMRC through Self Assessment.
This guide covers everything a UK sole trader needs to know about tax: what you owe, when you pay it, and how to reduce your bill legally.
How Sole Trader Tax Works
Your taxable profit is:
Taxable Profit = Total Business Income - Allowable Expenses
This profit is added to any other income you receive (employment income, investment income, rental income) to determine your total taxable income for the year. You then pay income tax and National Insurance on the result.
Income Tax Bands
Income Tax is charged in bands. In England, Wales and Northern Ireland the rates are 20% (basic rate), 40% (higher rate) and 45% (additional rate). Scotland sets its own rates and bands for non-savings income, so a Scottish taxpayer’s profits are taxed on the Scottish scale.
The personal allowance is the slice of income taxed at 0%. It is withdrawn by £1 for every £2 of income above £100,000, so very high earners lose it entirely. The band limits and the allowance are set by the government at each Budget, and HMRC publishes the figures for the current tax year on GOV.UK’s Income Tax rates page.
Example
To see how the bands work, take an illustrative personal allowance of £12,000 and a sole trader with £45,000 taxable profit and no other income:
| Band | Amount (£) | Rate | Tax (£) |
|---|---|---|---|
| Personal allowance | 12,000 | 0% | 0 |
| Basic rate | 33,000 | 20% | 6,600 |
| Total income tax | 6,600 |
Swap in the current allowance and band limits to get the real figure for the year.
National Insurance
Sole traders deal with two classes of National Insurance on their profits.
Class 4 NIC
Class 4 is the main National Insurance charge for the self-employed. It works like a second set of bands on top of Income Tax:
- No Class 4 is due on profits below the lower profits limit
- A main rate applies to profits between the lower and upper profits limits
- A much lower additional rate applies to profits above the upper limit
The limits and both rates are set by the government and can change from one tax year to the next. Class 4 is calculated on your Self Assessment return and paid with your Income Tax.
Class 2 NIC
Since 6 April 2024, self-employed people no longer have to pay Class 2. If your profits are at or above the small profits threshold, you are treated as having paid it and still build up State Pension entitlement. If your profits are below that threshold, you can choose to pay voluntary Class 2 to protect your State Pension and certain benefits. HMRC publishes the current threshold and weekly rate on GOV.UK.
Total Tax Example
Continuing the illustrative example with £45,000 profit, assume a Class 4 lower profits limit of £12,000 and a main rate of 6%:
| Tax | Calculation | Amount (£) |
|---|---|---|
| Income tax | As above | 6,600 |
| Class 4 NIC | (£45,000 - £12,000) x 6% | 1,980 |
| Total tax and NIC | 8,580 | |
| Effective tax rate | 19.1% |
The rates and limits in this example are for illustration only. Your accounting software or the HMRC calculation on your return will use the figures for the year.
Self Assessment
Key Dates
| Event | Deadline |
|---|---|
| Tax year ends | 5 April |
| Register for Self Assessment (first year) | 5 October following the tax year |
| Paper tax return | 31 October |
| Online tax return | 31 January |
| Pay balance of tax | 31 January |
| First payment on account | 31 January |
| Second payment on account | 31 July |
What You Report
On the self-employment supplementary pages (SA103):
- Turnover – your total business income
- Allowable expenses – categorised into the standard HMRC categories
- Net profit – the taxable figure
Since 6 April 2024 the cash basis has been the default for sole traders: you report income when received and expenses when paid. If you opt out and use the accruals basis, you report income when earned and expenses when incurred, regardless of when cash changes hands.
Payments on Account
If your Self Assessment tax bill exceeds £1,000 (and less than 80% of your tax was collected at source through PAYE), HMRC requires payments on account.
Each payment on account is 50% of the previous year’s tax bill, payable on:
- 31 January (during the tax year)
- 31 July (after the tax year ends)
Any remaining balance (or refund) is settled on the following 31 January when the actual tax return is filed.
Example
Your previous tax bill is £8,000. For the current tax year, you pay:
| Date | Payment | Amount (£) |
|---|---|---|
| 31 January | Previous-year balancing payment + first POA for current year | 8,000 + 4,000 = 12,000 |
| 31 July | Second POA for current year | 4,000 |
| Following 31 January | Current-year balancing payment (if tax bill is higher) | Varies |
The 31 January double payment in the first year catches many new sole traders off guard. Budget for it from the start.
Reducing Payments on Account
If you know your profits will be lower than the previous year, you can apply to reduce your payments on account through your HMRC online account. Be cautious – if you reduce them too much and your actual bill is higher, HMRC charges interest on the underpayment.
Allowable Expenses
Claiming every expense you are entitled to is the most direct way to reduce your tax bill. For a detailed breakdown, see our guide on tax-deductible expenses.
Key Categories
| Category | Examples |
|---|---|
| Office and premises | Rent, business rates, utilities, insurance |
| Home office | Simplified flat rate based on hours worked at home, or actual proportion of costs |
| Travel | Business mileage (55p/mile for the first 10,000 miles since 6 April 2026, 25p after), public transport, parking |
| Staff costs | Wages, employer NIC, pension contributions |
| Professional services | Accountancy fees, legal fees, professional subscriptions |
| Marketing | Website, advertising, business cards |
| Technology | Computers, software, phone (business proportion) |
| Insurance | Professional indemnity, public liability |
| Training | Job-related courses and qualifications |
What You Cannot Claim
- Client entertaining – meals and hospitality for clients
- Personal expenses of any kind
- Non-business clothing (uniforms and PPE are fine)
- Fines and penalties
- The personal element of mixed-use items (only claim the business proportion)
Trading Allowance
If your sole trader income is under £1,000 per year, it is completely tax-free under the trading allowance. You do not even need to register for Self Assessment.
If your income exceeds £1,000, you can choose to either:
- Deduct the £1,000 trading allowance instead of actual expenses (useful if expenses are minimal), or
- Deduct actual expenses in the normal way
You cannot use both.
Tax-Saving Strategies
1. Use the Marriage Allowance
If your spouse or civil partner earns less than the personal allowance, they can transfer 10% of the personal allowance to you, as long as you are a basic rate taxpayer. Your tax bill falls by 20% of the transferred amount each year you claim.
2. Pension Contributions
Personal pension contributions receive tax relief at your marginal rate:
| Contribution | Tax Relief (20% taxpayer) | Tax Relief (40% taxpayer) |
|---|---|---|
| £5,000 | £1,250 | £2,500 |
| £10,000 | £2,500 | £5,000 |
| £20,000 | £5,000 | £10,000 |
The pension provider claims basic rate relief automatically (you pay £8,000, they claim £2,000 from HMRC to make it £10,000). Higher-rate relief is claimed through your Self Assessment return.
3. Capital Allowances
If you buy equipment, vehicles or machinery for business use, claim capital allowances:
- Annual Investment Allowance – 100% deduction on qualifying assets up to £1,000,000
- Writing down allowance – a percentage of the remaining pool each year for amounts exceeding AIA, with a lower rate for the special rate pool
4. Consider Incorporation
If your profits consistently exceed £50,000, a limited company may reduce your overall tax bill. As a company director, you can take a small salary (within the NIC threshold) and the rest as dividends, which are taxed at lower rates than income tax plus NIC.
The saving depends on your profit level, how much you take out of the company and the tax rates for the year, so ask for a calculation based on your own numbers. The additional compliance costs of a limited company (annual accounts, Corporation Tax return, payroll) offset some of the saving.
5. Timing of Income and Expenses
If you use the cash basis, you have some control over timing:
- Delay invoicing near the year end to defer income to the next tax year
- Accelerate purchases before the year end to bring forward deductions
- Time large equipment purchases to fall in the year where you will benefit most from the deduction
This is legitimate tax planning, not avoidance. However, do not let tax timing override sound business decisions.
Making Tax Digital for Income Tax
MTD for Income Tax Self Assessment (MTD ITSA) requires sole traders and landlords to keep digital records and submit quarterly updates to HMRC once their qualifying income passes the threshold. It applies from 6 April 2026 above £50,000, from 6 April 2027 above £30,000 and from 6 April 2028 above £20,000.
Under MTD ITSA:
- You submit quarterly summaries of income and expenses to HMRC (not full tax returns)
- You submit an end of period statement and a final declaration after the year end
- You must use MTD-compatible software
For those in scope, this replaces the old annual-only Self Assessment cycle with more frequent reporting.
Common Tax Mistakes
- Not registering for Self Assessment on time – register by 5 October following the tax year you started trading; late registration leads to penalties
- Missing the 31 January deadline – automatic £100 penalty for one day late, rising sharply over time
- Not budgeting for payments on account – the first 31 January “double payment” is the biggest cash flow shock for new sole traders
- Under-claiming expenses – review your bank statements methodically; many sole traders miss legitimate deductions
- Mixing personal and business finances – use a separate bank account to make record keeping simple
- Not keeping receipts – no receipt means no deduction if HMRC enquires
- Ignoring National Insurance – Class 4 NIC comes on top of income tax; factor it into your tax projections