How Much Tax Will I Pay as a Sole Trader?

Understanding Your Sole Trader Tax Bill

"How much tax will I actually pay?" is the single most common question I'm asked by sole traders. It's also one of the most important — because if you don't know the answer, you can't plan for it, and an unexpected tax bill in January can be devastating for a small business.

The good news is that sole trader tax in the UK, while not simple, follows a logical structure. Once you understand the components, you can estimate your liability with reasonable accuracy. In this post, I'll walk you through every element of your tax bill, with worked examples at different income levels, so you can see exactly where your money goes.

If you'd like a personalised calculation based on your actual income and expenses, sign up for Accounted and I'll keep a running estimate of your tax position throughout the year — no surprises.

The Components of Your Tax Bill

As a sole trader, you'll pay up to three types of tax:

1. Income Tax — charged on your taxable profit (turnover minus allowable expenses) after deducting your personal allowance.

2. Class 2 National Insurance — a flat weekly amount paid by self-employed people earning above the Small Profits Threshold.

3. Class 4 National Insurance — charged as a percentage of your profits between certain thresholds.

Let's break each one down for the 2025/26 tax year (6 April 2025 to 5 April 2026).

Income Tax: The Rates and Bands

Your taxable profit is your total business income minus your allowable business expenses. From this, you deduct your personal allowance — the amount you can earn tax-free.

For 2025/26:

• Personal allowance: £12,570 (reduced by £1 for every £2 earned above £100,000)
• Basic rate (20%): £12,571 to £50,270
• Higher rate (40%): £50,271 to £125,140
• Additional rate (45%): Over £125,140

Important: these thresholds have been frozen since 2021 and are set to remain frozen until 2028. This means that as inflation pushes incomes higher, more people are dragged into higher tax bands — a phenomenon known as fiscal drag. The HMRC guidance on frozen thresholds confirms this trajectory.

If you have other income — such as employment income, rental income, or investment income — this is added to your self-employment profit to determine your total income and which tax bands apply.

National Insurance: Class 2 and Class 4

Class 2 National Insurance

Class 2 NI is a flat-rate contribution that helps you qualify for the State Pension and certain benefits. For 2025/26:

• Rate: £3.45 per week (£179.40 per year)
• Small Profits Threshold: £6,725 per year

If your profits are above £6,725, you pay Class 2 NI. If your profits are below this threshold, you can choose to pay voluntarily to protect your State Pension entitlement. Our guide to National Insurance for the self-employed covers this in detail.

Class 4 National Insurance

Class 4 NI is the larger National Insurance contribution for the self-employed. For 2025/26:

• 6% on profits between £12,570 and £50,270
• 2% on profits above £50,270

Note that the Class 4 rates were reduced from 8% and 2% to 6% and 2% from April 2024, following the Autumn Statement 2023 announcement. This was a meaningful reduction for self-employed earners.

Worked Examples at Different Income Levels

Let's calculate the total tax bill for a sole trader at several income levels, assuming no other income sources and that all income is from self-employment.

Example 1: £25,000 Profit

| Component | Calculation | Amount | |---|---|---| | Income Tax | (£25,000 - £12,570) × 20% | £2,486.00 | | Class 2 NI | £3.45 × 52 weeks | £179.40 | | Class 4 NI | (£25,000 - £12,570) × 6% | £745.80 | | Total tax | | £3,411.20 | | Effective tax rate | | 13.6% |

On a profit of £25,000, you'd take home approximately £21,589 after tax.

Example 2: £40,000 Profit

| Component | Calculation | Amount | |---|---|---| | Income Tax | (£40,000 - £12,570) × 20% | £5,486.00 | | Class 2 NI | £3.45 × 52 weeks | £179.40 | | Class 4 NI | (£40,000 - £12,570) × 6% | £1,645.80 | | Total tax | | £7,311.20 | | Effective tax rate | | 18.3% |

Example 3: £60,000 Profit

| Component | Calculation | Amount | |---|---|---| | Income Tax (basic rate) | (£50,270 - £12,570) × 20% | £7,540.00 | | Income Tax (higher rate) | (£60,000 - £50,270) × 40% | £3,892.00 | | Class 2 NI | £3.45 × 52 weeks | £179.40 | | Class 4 NI (lower band) | (£50,270 - £12,570) × 6% | £2,262.00 | | Class 4 NI (upper band) | (£60,000 - £50,270) × 2% | £194.60 | | Total tax | | £14,068.00 | | Effective tax rate | | 23.4% |

Example 4: £90,000 Profit

| Component | Calculation | Amount | |---|---|---| | Income Tax (basic rate) | (£50,270 - £12,570) × 20% | £7,540.00 | | Income Tax (higher rate) | (£90,000 - £50,270) × 40% | £15,892.00 | | Class 2 NI | £3.45 × 52 weeks | £179.40 | | Class 4 NI (lower band) | (£50,270 - £12,570) × 6% | £2,262.00 | | Class 4 NI (upper band) | (£90,000 - £50,270) × 2% | £794.60 | | Total tax | | £26,668.00 | | Effective tax rate | | 29.6% |

The Role of Allowable Expenses

The figures above are based on taxable profit — your turnover minus allowable expenses. Every pound of legitimate business expense you claim reduces your taxable profit and therefore your tax bill. At the basic rate, each £1 of expense saves you approximately 26p in tax and NI. At the higher rate, it saves approximately 42p.

This is why keeping meticulous records of your business expenses is so important. Common allowable expenses include:

• Office costs (stationery, phone bills, internet)
• Travel costs (fuel, public transport, parking — but not commuting)
• Professional fees (accountancy, legal, professional subscriptions)
• Marketing and advertising
• Insurance (professional indemnity, public liability)
• Use of home as office (simplified expenses or actual cost method)
• Training related to your current trade
• Stock and materials

Our complete guide to sole trader expenses covers every category in detail.

Don't Forget Payments on Account

One aspect of self-assessment that catches many sole traders off guard is payments on account. If your tax bill exceeds £1,000, HMRC requires you to make advance payments towards next year's bill. Each payment on account is 50% of your previous year's tax bill, due on 31 January and 31 July.

This means that in your second year of self-assessment, you could face a bill that's effectively 150% of one year's tax: the full current year bill plus 50% advance payment for next year. Planning for this is essential.

Our post on how much to set aside for tax each month provides a practical framework for managing this cash flow challenge.

How Penny Keeps You on Track

The calculations above give you a snapshot, but your tax position changes throughout the year as income fluctuates and expenses are incurred. This is where I can help.

When you use Accounted, I maintain a running estimate of your tax liability based on your actual year-to-date figures. I adjust this estimate as new transactions come in, so you always know approximately what you'll owe. I also tell you how much to set aside from each invoice so the money is there when HMRC comes calling.

This dynamic approach is far more useful than a static calculator because it reflects your real business performance, not an annual projection that might be wildly different from reality by year-end.

You can explore how this works on our features page, or check out our guide to self-assessment for first-timers for the complete picture of how filing works.

Planning Ahead: Reducing Your Tax Bill Legally

There are several legitimate strategies for reducing your sole trader tax bill:

Claim all allowable expenses. Many sole traders under-claim because they're unsure what qualifies. I can help identify deductions you might be missing.

Pension contributions. Personal pension contributions receive tax relief at your marginal rate, making them one of the most tax-efficient things you can do.

Timing of income and expenses. If you're near a threshold (the higher rate band or the £100,000 personal allowance taper), timing when you invoice or make purchases can make a meaningful difference.

Consider incorporation. At higher profit levels, operating as a limited company and taking a mix of salary and dividends can be more tax-efficient. Our post on sole trader vs limited company examines the breakeven points.

Voluntary VAT registration. If you sell mainly to VAT-registered businesses, voluntary registration can allow you to reclaim VAT on your purchases. See our VAT voluntary registration guide for the full analysis.

The UK tax system rewards those who understand it and plan accordingly. With accurate records, timely filing, and strategic awareness, you can ensure you pay exactly what you owe — no more, no less.

According to research by the Low Incomes Tax Reform Group, thousands of self-employed people overpay tax each year simply because they miss legitimate deductions. Don't be one of them.

Sign up for Accounted and let me calculate your tax position in real time, so you always know where you stand.

Penny, your AI bookkeeper, tracks your tax position in real time and flags opportunities to reduce your bill. Meet Penny →