Sole Trader Tax Calculator UK
Calculate your sole trader tax liability including income tax and National Insurance. Our calculator helps you understand your tax position based on your turnover, expenses, and allowances.
Practical calculator guidance
Preparing a reliable sole-trader estimate
A sole trader is taxed on business profit, not simply on cash withdrawn from the business. Build the estimate from complete gross income and supported allowable costs for the tax year, then consider employment, property or other income separately where it affects the wider tax position.
Turnover is not the same as profit
Turnover is the amount earned from customers before business expenses. Bank deposits can be lower because payment processors deduct fees, or higher because they include loans and personal transfers. Reconcile invoices, sales records and platform reports before entering turnover. Then classify business costs and exclude drawings, personal spending and loan repayments that are not allowable expenses.
Use evidence for mixed and unusual costs
Software, advertising, insurance, professional fees, stock and business travel may be straightforward. Home working, vehicles, phones, internet and equipment can involve private use, simplified expenses or capital rules. Keep the calculation that supports the amount entered. Losses, pre-trading costs, grants and substantial equipment purchases may require tax treatment not captured by one expense box.
Plan for Self Assessment cash flow
Income Tax and self-employed National Insurance are normally settled through Self Assessment rather than deducted from each customer payment. A first large balancing payment may also trigger payments on account. Update the estimate during the year, maintain a separate tax reserve and use the payment calculators to understand January and July timing. The estimate is not the amount formally due until HMRC processes the return.
Worked example
A consultant invoices £32,000 and has £4,800 of supported software, insurance, travel and professional costs. The provisional profit is £27,200. They do not subtract personal drawings and do not use net bank deposits as turnover. PAYE income from an earlier job is considered in the final return, while the calculator gives a starting estimate of tax and National Insurance on the business profit.
Sole trader tax guide
A sole trader is someone who runs their own business as an individual. You keep all profits after tax, but you're personally responsible for any losses. You must register with HMRC as self-employed and file a self-assessment tax return each year, reporting your business income and expenses.
Allowable business expenses are costs wholly and exclusively for your business. Common examples include office costs, travel expenses (not commuting), equipment, professional fees, marketing, insurance, and business premises costs. You can also claim a proportion of home office expenses if you work from home. Keep detailed records and receipts for all claimed expenses.
The standard Personal Allowance is £12,570 for 2026/27 and tapers once adjusted net income exceeds £100,000. The pension field provides a simplified adjustment for a gross personal contribution; the exact relief method depends on how the pension scheme receives the payment.
Class 4 National Insurance for 2026/27 is estimated at 6% on profits between £12,570 and £50,270, then 2% above £50,270. Class 2 is not added as a mandatory charge; eligible people with lower profits can consider voluntary Class 2 at £3.65 a week. Filing and payment deadlines depend on the tax year and your circumstances, so check the linked HMRC guidance.
Example scenario
Freelance consultant
Related calculators and guides
How this guidance is reviewed
Author
Written and maintained by UK Tax Toolbox, led by founder Conor Dwyer. Calculator assumptions are checked against the public sources linked on the page.
Last reviewed
12 August 2026
Basis of guidance
Public HMRC and GOV.UK guidance, published tax thresholds and the calculator assumptions stated on each page.
Useful official references
Spot something that looks out of date? Use the contact page to flag corrections. Important tax decisions should still be checked with HMRC or a qualified adviser.