Setting Up as a Self-Employed Tradesman
TL;DR
Around 35–40% of UK construction workers are self-employed (ONS Labour Force Survey). To trade legally as a sole trader you must register for Self Assessment with HMRC by 5 October following the end of the tax year you started, register for CIS if you do construction work, pay Class 2 (where applicable) and Class 4 National Insurance, and consider VAT (mandatory if turnover exceeds £90,000). You should also have public liability insurance (typically £1m–£5m), keep clear records (HMRC's Making Tax Digital rules apply), and choose between sole trader, partnership or limited company.
Table of Contents
1. Choosing the Right Business Structure
The three main options are sole trader, partnership and limited company. Each has different rules, tax treatments and liabilities. HMRC and Companies House publish detailed guidance on each at GOV.UK, and the British Business Bank's Business Finance Guide is a useful neutral resource.
As a sole trader, you and the business are legally the same. You are personally liable for any debts. Set-up is simple — register for Self Assessment with HMRC and you're trading. Most self-employed tradespeople start here, and ONS data shows the majority remain sole traders throughout their career.
A partnership is similar but with two or more people sharing profits and liabilities. The Partnership Act 1890 governs how unincorporated partnerships work. You should always have a written partnership agreement — handshake partnerships routinely end badly when one party leaves or dies.
A limited company is a separate legal entity. You become a director and shareholder. The company pays Corporation Tax (currently 19% for small profits up to £50,000, rising on a sliding scale to 25% above £250,000) and you take income through a mix of salary and dividends. It involves more paperwork (annual accounts, confirmation statements, payroll) but offers limited liability and can be more tax-efficient at higher profit levels — subject to IR35.
2. Registering with HMRC
If you start working for yourself, HMRC requires you to register for Self Assessment by 5 October following the end of the tax year (which runs from 6 April to 5 April) in which you became self-employed. You can do this online via GOV.UK and you'll be issued a Unique Taxpayer Reference (UTR).
If you do construction work, you should also register for the Construction Industry Scheme (CIS) — even if you're not legally required to, registration drops your CIS deduction rate from 30% to 20%, which is a major cash flow improvement. Our CIS guide covers this in full.
For a limited company, you also need to register with Companies House (£12 online), set up PAYE if you're going to take a salary, and register the company for Corporation Tax with HMRC within 3 months of starting to trade. Failing to register on time triggers automatic penalties.
Late registration penalties can stack up. HMRC's "failure to notify" penalty regime can charge a percentage of the tax owed plus daily penalties for prolonged failure. It is dramatically cheaper to register on time than to wait until the first tax bill arrives.
3. Income Tax and National Insurance
As a self-employed tradesman you pay Income Tax on your trading profits — that is, income minus allowable business expenses — at the standard rates (currently 20% basic, 40% higher and 45% additional in England, Wales and Northern Ireland; Scotland has different bands). The personal allowance for 2024/25 is £12,570.
National Insurance for the self-employed has changed in recent years. From April 2024, Class 2 NICs were abolished as a mandatory contribution for most self-employed people earning above the Small Profits Threshold, though those below the threshold can still pay voluntarily to protect their state pension entitlement.
Class 4 NICs are paid on profits above a Lower Profits Limit. The current rates and thresholds are published on GOV.UK and change at each Budget. As of 2024/25, the main Class 4 rate is 6% on profits between the lower and upper limits, plus 2% on profits above the upper limit.
Self Assessment tax bills are due in two payments on account (31 January and 31 July) plus a balancing payment. CIS deductions taken from your pay during the year count as advance payments toward your bill. Many tradespeople over-pay through CIS and receive refunds after submitting their tax return.
4. VAT, Reverse Charge and Making Tax Digital
You must register for VAT if your VAT-taxable turnover exceeds the registration threshold (£90,000 from 1 April 2024) in any rolling 12-month period, or if you expect to exceed it in the next 30 days. Voluntary registration below the threshold is also possible and can be advantageous if you mainly work for VAT-registered clients.
The construction industry has a special rule: the VAT domestic reverse charge for construction services, in force since 1 March 2021. In most B2B construction supplies, the customer (not the supplier) accounts for the VAT to HMRC. HMRC publishes detailed flow charts on GOV.UK to help work out when it applies.
Making Tax Digital (MTD) for VAT requires VAT-registered businesses to keep digital records and submit returns through compatible software. MTD for Income Tax Self Assessment is being phased in for sole traders and landlords with qualifying income above set thresholds — currently £50,000 from April 2026 and £30,000 from April 2027 (subject to legislation).
The practical message: get accounting software (FreeAgent, Xero, QuickBooks etc) sooner rather than later, and treat MTD as a "when", not an "if". HMRC publishes a list of MTD-compatible software and many providers offer discounts for sole traders.
5. Insurance You Actually Need
Public Liability Insurance covers claims by clients or members of the public for injury or property damage caused by your work. Most main contractors and many domestic clients now demand at least £2 million of PL cover, with £5 million common for larger sites and £10 million required for some Tier 1 work.
Employers' Liability Insurance is a legal requirement under the Employers' Liability (Compulsory Insurance) Act 1969 if you employ anyone, even casually. The minimum statutory cover is £5 million but most policies provide £10 million as standard. Failure to hold ELI can attract HSE fines of up to £2,500 per day uninsured.
Tools and equipment insurance covers theft and damage to your tools, which is a very real risk — the Office for National Statistics' Crime Survey for England and Wales has consistently shown vehicle and tool theft as significant problems for tradespeople, especially in urban areas.
Other policies to consider include Professional Indemnity (for designers, surveyors and consultants), Income Protection (vital if you have dependants and no employer sick pay) and contract works insurance for larger one-off projects. Brokers regulated by the Financial Conduct Authority can compare options for you.
6. Cash Flow, Records and Common Mistakes
Open a separate business bank account from day one — even as a sole trader, where it isn't legally required. Mixing personal and business spending is the single biggest cause of accounting errors and missed deductions among small tradespeople, according to most high-street accountancy practices.
Keep every receipt for at least 6 years (HMRC's standard record-keeping requirement for businesses). Apps such as Dext, AutoEntry and many accounting platforms let you photograph receipts as you go, removing the shoebox problem entirely.
Set aside tax with every payment. A simple rule of thumb is to move 25–30% of every net invoice into a separate savings account on the day it lands. This avoids the all-too-common scenario of facing a five-figure Self Assessment bill in January with nothing in the account to pay it.
Finally, get an accountant. Even a basic annual fee of a few hundred pounds usually pays for itself in tax savings, avoided penalties and time recovered. Look for one with construction-specific experience, particularly in CIS, the VAT reverse charge and IR35.