Why is 20% taken off my roofing payments?

That is the CIS deduction. Contractors take 20% from a registered subcontractor's labour and pay it to HMRC against your tax. It is 30% if you are not CIS-registered, which is why registering is worth doing.

Is CIS deducted on materials too?

No. The deduction is on the labour element of a payment, not the materials. Splitting labour and materials clearly on your invoices means CIS is only taken on your labour, not the whole job.

Do I become a contractor if I pay another roofer?

Yes. As soon as you pay another roofer or labourer to work under you, you are a contractor for CIS: you must verify them, deduct the right rate, and file a monthly return. Many roofing firms are subcontractor and contractor at once.

Does the CIS deduction mean I have paid my tax?

Rarely in full. The 20% is taken before your personal allowance and expenses, so it usually exceeds your real tax. The difference comes back as a refund once your return is filed.

CIS for Roofers, Explained

Written and reviewed by the Roofer Accountants editorial team. Last reviewed 29 July 2026.

Almost every roofer meets CIS, the Construction Industry Scheme, from their first subcontract job. It is the reason 20% vanishes from your payments before you see them, and, for most sole-trader roofers, the reason you are owed money back at the end of the year.

This is how CIS works for a roofer specifically: what gets deducted, what it is taken on, and why the deduction is rarely your real tax bill.

The Deduction on a Roofer's Payments

When you work as a subcontractor for a contractor, they deduct CIS from what they pay you and send it to HMRC against your tax. If you are registered under CIS the rate is 20%; if you are not registered it is 30%, which is the first reason to register. With gross payment status it is 0%, covered in its own guide.

The deduction is taken on the labour element of the payment, not the materials. So if you invoice for a re-roof with the felt, battens and tiles itemised separately, the CIS is calculated on your labour, not the whole invoice. Getting that split right on your invoices directly reduces what is held back.

Subcontractor or Contractor, or Both

Most roofers start as subcontractors, paid under deduction by a builder or a main contractor. The moment you pay another roofer or labourer to work under you, you also become a contractor for CIS, and you have to verify them with HMRC, deduct the right rate, and file a monthly return. Plenty of growing roofing firms are both at once.

The two sides are handled differently, and the contractor side carries deadlines and penalties a sole subcontractor never sees. Our CIS service covers whichever side, or both, applies to you.

Why the Deduction Is Not Your Tax Bill

This is the part that matters most for a subcontractor roofer. The 20% is deducted from your gross labour, before your personal allowance and before a single expense. Your actual tax is worked out on your profit after all of that: van, tools, materials you bought, insurance and the rest.

Because the deduction ignores all your costs and your tax-free allowance, it almost always adds up to more than you really owe. The difference comes back as a refund when your Self Assessment return is filed.

Registering and Getting It Right

Register as a CIS subcontractor so you are deducted at 20% rather than 30%, keep every payment and deduction statement a contractor gives you, and keep your invoices splitting labour from materials. Those three habits are most of what keeps CIS straight for a roofer.

If you engage other roofers, the contractor obligations start, and those are worth handing over rather than missing a monthly return. To get your CIS in order, tell us how you work.