UK Self-Employed Tax Calculator

You pay tax through Self Assessment, once a year, rather than through PAYE. You register with HMRC as self-employed, keep records of your income and expenses through the tax year, then file a Self Assessment return by 31 January following the end of the tax year (the tax year runs 6 April to 5 April). Any tax you owe for that year, Income Tax plus Class 4 National Insurance, is due on the same 31 January deadline.

Most sole traders also fall into the payments-on-account system from their second year onward. HMRC asks you to pay half of your estimated next year's tax bill on 31 January and the other half on 31 July, on top of whatever you owe for the year just finished. This means your first Self Assessment bill can be roughly one and a half times a single year's actual liability: the balance for year one, plus your first payment on account toward year two. This catches a lot of first-year sole traders off guard, so it is worth setting aside more than just your calculated tax figure in your first year.

A sole trader (this calculator) and a limited company contractor are two entirely different legal and tax structures, even though both are commonly called 'self-employed' or 'contracting' in everyday conversation. A sole trader has no separate legal entity from the individual, pays Income Tax and Class 4/2 NI directly on profit through Self Assessment, and IR35 does not apply because there is no company to fall inside or outside of.

A limited company contractor runs their own company, which invoices clients, pays Corporation Tax on company profit, and then the individual draws income from the company as salary and dividends (or, if working through certain end clients, may be caught by IR35 rules that tax them closer to an employee). If you are working through your own limited company or via an umbrella company, this sole trader calculator is the wrong tool: use our IR35 calculator or UK take-home calculator instead, which model that structure correctly.

Allowable expenses are costs that are wholly and exclusively for running your business, and HMRC lets you deduct them from revenue before calculating taxable profit. Common examples for self-employed professionals include a proportionate share of home office costs (rent, utilities, internet), business travel and mileage (at HMRC's approved mileage rates), equipment and software subscriptions used for work, professional indemnity insurance, accountancy fees, marketing and website costs, and training directly related to your trade.

Costs that are not allowable include your own salary or drawings, personal living expenses, client entertainment (with narrow exceptions), and fines or penalties. If you are unsure whether a cost qualifies, HMRC's guidance on simplified expenses and allowable business expenses for the self-employed is the definitive reference, and an accountant is worth the fee if your expense mix is complex.

You must register for VAT once your taxable turnover (not profit) exceeds £90,000 in any rolling 12-month period, not just your accounting year. You have 30 days from the point you realise you will cross the threshold to register, and once registered you must charge VAT on your invoices (usually 20%) and can reclaim VAT on eligible business purchases. Many freelancers and consultants also choose to register voluntarily below the threshold if most of their clients are VAT-registered businesses, since it makes the VAT charged largely a pass-through cost.

This calculator does not model VAT-registered trading. It assumes revenue and profit figures are your actual take from the business, not the mechanics of collecting and remitting VAT on top of your fees.

Class 4 National Insurance is charged on your annual profit at 6% on profit between the Lower Profits Limit of £12,570 and the Upper Profits Limit of £50,270, and at 2% on any profit above £50,270. It is collected automatically as part of your Self Assessment bill alongside Income Tax, so you do not pay it separately. There is no Class 4 charge at all on profit below £12,570.

Mandatory flat-rate Class 2 was abolished from April 2024. From 2026/27, if your profits are at or above the Small Profits Threshold of £7,105, you get a National Insurance credit automatically, a qualifying year toward your State Pension and contributory benefits, at no cost. You do not need to do anything or pay anything to get this credit.

If your profits are below £7,105, you do not receive that credit automatically, but you can choose to pay voluntary Class 2 contributions at £3.65 a week (£189.80 a year) to protect your State Pension record for that year. This is most relevant to sole traders with a low-profit year, a new business, or a side venture alongside other income.

As an employee, your employer deducts Income Tax and Class 1 National Insurance automatically through PAYE before you are paid, and your employer separately pays Employer National Insurance on top of your salary (a cost you never see directly). As a sole trader, nothing is deducted at source: you receive your full revenue, keep records, calculate your own Income Tax and Class 4/Class 2 National Insurance liability, and pay it in arrears through Self Assessment.

The rates also differ. Employees pay Class 1 NI at 8% up to the Upper Earnings Limit and 2% above it; sole traders pay Class 4 NI at 6% and 2% at the same thresholds, so the NI rate is typically lower for the same profit level. However, sole traders get no employer pension contribution, no statutory sick pay, no holiday pay, and no redundancy protection, all of which have real financial value that a headline take-home comparison does not capture.

Yes. The main legitimate levers are claiming every allowable business expense you are entitled to, contributing to a personal pension (which extends your basic rate band and can pull income out of higher-rate tax), using the Marriage Allowance if your spouse is a lower earner, and, if your trading structure and profit level justify it, considering incorporation as a limited company where Corporation Tax and dividend tax rates might work out lower than sole trader Income Tax and Class 4 NI. Incorporation is not automatically better and depends heavily on your specific profit level and plans, so it is worth running the numbers or speaking to an accountant before switching structures.