Do Subcontractors Pay 40% Tax? UK Construction CIS FAQ

If you work in UK construction as a subcontractor, sole trader or limited company director, tax can quickly get confusing. A lot of tradespeople hear about “40% tax” and assume that all self-employed income gets taxed at that rate, or that CIS deductions mean they are losing nearly half their money. This FAQ explains what tax subcontractors actually pay, when the 40% higher-rate band applies, and how to manage your income properly. We have kept it practical, with examples from real site situations, and highlighted where SiteSamurai helps contractors and subcontractors stay on top of records, payments and compliance.

Frequently Asked Questions

What tax do subcontractors pay?

Subcontractors in UK construction do not automatically pay 40% tax. What they pay depends on their business setup, total income and whether they are registered under the Construction Industry Scheme (CIS). In most cases, a self-employed subcontractor pays:

• Income Tax on profits, not turnover
• Class 2 and Class 4 National Insurance, where applicable
• CIS deductions at source if working for a contractor
• Corporation Tax instead, if trading through a limited company

Under CIS, contractors usually deduct:

• 20% if the subcontractor is registered for CIS
• 30% if they are not registered
• 0% in some gross payment status cases

That CIS deduction is not the same as your final tax bill. It is more like an advance payment towards tax and National Insurance. For example, if a bricklaying subcontractor on a housing site invoices £2,000 labour and £300 materials, CIS is normally applied to the labour element only. So the deduction would usually be 20% of £2,000, not 20% of the full £2,300.

Your final tax bill is then worked out through Self Assessment based on actual profit after allowable expenses such as tools, van costs, PPE, insurance and mileage. If your profit is modest, you may stay entirely within the basic rate band. If it is higher, some of it may fall into the 40% band.

This is where paperwork matters on site. Missed invoices, poor records and unclear labour-versus-material splits can lead to over-deductions or cashflow headaches. SiteSamurai helps construction firms keep payment records, job costs and subcontractor documentation organised, making it easier to reconcile CIS deductions and avoid disputes at month end.

Do you get taxed 40% when self-employed?

No, being self-employed does not mean you automatically get taxed at 40%. In the UK, self-employed people pay tax using the same income tax bands as employees. The 40% rate only applies to the part of your taxable income that falls above the higher-rate threshold, not to everything you earn.

In practical terms, this means:

• You pay tax on profit, not total sales
• Allowable business expenses reduce taxable profit
• Only income within the higher-rate band is taxed at 40%
• Lower portions of income are taxed at the lower rates first

For example, imagine a drylining subcontractor working across two commercial fit-out sites brings in £78,000 over the year. After deducting legitimate business costs such as fuel, tools, public liability insurance, mobile phone use and accountancy fees, their taxable profit might be £52,000. In that case, only the portion above the basic rate threshold would be taxed at 40%, not the full £52,000.

This is why good record-keeping is essential in construction. Many subcontractors look at gross payments coming in from a principal contractor and think they are in the 40% bracket, when in reality expenses and CIS deductions change the picture significantly. Site delays, rework, travel between sites and plant hire can all affect your real profit.

SiteSamurai helps by giving construction businesses better visibility over project costs, subcontractor payments and supporting records. When your site admin is in order, it is much easier to understand what you have actually earned, what has been deducted under CIS, and whether any of your profit genuinely falls into the 40% band.

How to avoid 40% tax on salary?

You cannot simply ‘avoid’ 40% tax if your taxable income genuinely falls into the higher-rate band, but you can manage income efficiently and legally. For construction business owners, especially those running limited companies, the key is tax planning rather than tax avoidance.

Common legitimate options include:

• Keeping accurate expense records so taxable profit is not overstated
• Making pension contributions, which can reduce taxable income
• Taking advice on the balance between salary and dividends if you operate through a limited company
• Timing bonuses or drawings carefully across tax years where appropriate
• Using all available allowances correctly

For example, a groundwork contractor who is also a director may pay themselves a modest salary and then take dividends, rather than drawing everything as PAYE salary. That can be more tax-efficient, depending on profits and personal circumstances. A sole trader, on the other hand, cannot split income into salary and dividends in the same way, but they can still reduce taxable profit by claiming legitimate construction-related costs properly.

On site, problems often arise because records are poor. A contractor might forget to log plant hire, small tool purchases, parking, training certificates or protective clothing, and then ends up appearing more profitable on paper than they really are. That can push more income into the higher-rate band than necessary.

SiteSamurai helps construction firms keep job costs, purchase records, labour tracking and site paperwork in one place. That gives a clearer view of margins before year end and supports better conversations with your accountant. The result is practical tax planning, stronger cashflow control and fewer nasty surprises when returns are due.

Understanding whether subcontractors pay 40% tax comes down to knowing the difference between CIS deductions, taxable profit and the UK tax bands. If your records are accurate, your costs are tracked properly and your site paperwork is under control, tax becomes far easier to manage. SiteSamurai helps construction businesses stay organised, improve visibility on labour and costs, and reduce admin headaches across every job. If you want tighter control over subcontractor payments and project records, now is a good time to see how SiteSamurai can help.