CIS explained for subcontractors

Under the Construction Industry Scheme, tax is taken from your pay before you get it. Here’s how it works — and why you often get some back.

Updated July 2026 · A general guide, not personal tax advice.

What is the CIS?

The Construction Industry Scheme (CIS) is how HMRC collects tax from construction subcontractors. When a contractor pays you, they deduct tax at source (commonly 20% if you’re registered, 30% if not) and pay it to HMRC on your behalf. That deduction counts towards your eventual tax bill.

Why you may be owed a refund

CIS is deducted from your gross pay, before any expenses or your tax-free personal allowance are taken into account. So once you factor in your allowance and allowable costs (tools, materials, van, mileage, PPE), you’ve often overpaid — and Self Assessment is how you claim the difference back.

Expenses you can usually claim

• Tools, equipment and their repair
• Protective clothing and safety gear (PPE)
• Materials you paid for
• Van running costs or business mileage
• Public liability insurance and professional fees

Getting it right

Keep every receipt and record the CIS already deducted. FTrak accounts for CIS deductions, tracks your expenses and mileage, and shows your estimated position — including any likely refund — then files your Self Assessment to HMRC. See FTrak for CIS subcontractors.