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CIS deduction calculator
Subcontracting under the Construction Industry Scheme? See exactly what the contractor will hold back and what lands in your account — and remember: materials are yours in full, and the deduction is tax you've already paid.
Materials you paid for are excluded from the deduction — keep the receipts.
How it breaks down
| Invoice total | £2,000 |
| Materials (no deduction) | £400 |
| Labour (deduction applies) | £1,600 |
| CIS deducted (20%) | −£320 |
The deduction isn't lost — it's tax paid in advance, offset against your Income Tax and National Insurance at Self Assessment. Many subcontractors are owed a refund.
Register — it's 10% of your money
Unregistered subcontractors lose 30% instead of 20% — on £40,000 of labour a year, that's £4,000 extra held back until Self Assessment. Registering with HMRC is free and takes minutes. Established firms with a clean record can apply for gross payment status and receive everything, settling tax later.
Most subbies are owed a refund
CIS deducts a flat rate from labour with no personal allowance and no expenses — so at Self Assessment, once your allowance, van, tools and materials are counted, many subcontractors have overpaid and are due money back. File early; refunds are usually quick.
Guide, not tax advice. Pricing a job first? Try the job cost calculator.