CIS Construction Industry Scheme: Registration, Deductions and Monthly Returns Explained
Quick Answer: The Construction Industry Scheme (CIS) is HMRC's tax-deduction scheme for payments by contractors to subcontractors in UK construction. Registered subcontractors are deducted at 20%; unregistered at 30%; gross-payment-status subcontractors at 0%. Contractors must verify each subcontractor with HMRC, deduct tax from labour element of payments (not materials), submit a monthly CIS300 return by the 19th of each month following the tax month, and issue a payment and deduction statement to each subcontractor. Penalties for late returns start at £100 and escalate. Both contractors and subcontractors must register; sole traders, partnerships and limited companies all fall within scope.
Summary
CIS is the UK construction industry's specific PAYE-equivalent for subcontractor payments, and it catches almost every UK building business at some point. If you pay subcontractors for construction work, you're a CIS contractor and must register, verify, deduct and report. If you accept payment for construction work as a subcontractor, you're under CIS and must register to avoid the higher 30% deduction rate. The scheme has been in place since 1971 (current version since April 2007) and is enforced rigorously by HMRC.
The pricing implication for trades is significant. A subcontractor working through CIS sees 20% (or 30%) of their labour element deducted from each payment by the contractor; HMRC holds it; the subcontractor reclaims it through their Self Assessment or Corporation Tax return at year end. Cash flow is materially affected — subbies effectively give a 12-month interest-free loan to HMRC.
The other operational reality is that CIS catches activities tradespeople don't always recognise as "construction": refurbishment, alterations, decorating, demolition, ground works, civil engineering. Repairs to manufactured plant aren't in scope; routine cleaning isn't (usually); but anything affecting the fabric of a building generally is. Get the scope wrong and HMRC penalties accumulate fast.
Key Facts
- CIS rate — registered subcontractor — 20% deduction from labour element of payment
- CIS rate — unregistered subcontractor — 30% deduction from labour element
- CIS rate — gross payment status (GPS) subcontractor — 0% deduction
- Registration deadline — before the first payment is made/received
- Verification — contractor must verify each subbie with HMRC before first payment
- Monthly return — CIS300 due by 19th of month following the tax month (5th–4th)
- Tax month — runs 6th of one month to 5th of next
- Payment and deduction statement — must be issued to subbie within 14 days of tax month end
- Late return penalty — £100 immediately, £200 after 2 months, £300 or 5% (whichever higher) after 6 months
- Reverse charge VAT — applies to most CIS supplies between VAT-registered businesses since 1 March 2021
- Materials — not subject to CIS deduction; must be itemised separately on invoices
- Labour-only contractors — fully in scope
- Public bodies as contractors — schools, councils all in scope
- GPS qualifying turnover — £30,000+ labour for sole trader; £30,000 × number of partners for partnership; £30,000 × number of relevant persons for company
- GPS compliance test — clean PAYE/SA history with HMRC
- GPS application — apply via HMRC online; assessed on compliance + business + turnover tests
Quick Reference Table — CIS Status and Rates
Need to quote compliant work? squote includes relevant regulations in your quotes.
Try squote free →| Subbie status | Deduction | When this applies |
|---|---|---|
| Gross Payment Status (GPS) | 0% | Subbie holds GPS approval from HMRC |
| Registered (standard) | 20% | Subbie registered as net rate |
| Unregistered | 30% | Subbie has not registered with HMRC |
| Materials portion | 0% | Tax never deducted from materials cost |
Detailed Guidance
Who needs to register as a contractor
A "contractor" under CIS is anyone who pays for construction operations — including:
- Construction companies and developers
- Property developers
- Local authorities
- Government departments
- Housing associations
- Architects (when commissioning works)
- Mainstream businesses spending £3m+/year on construction
Most subcontractors who hire other subbies become contractors at the same time. Registration: HMRC online via Government Gateway.
Who needs to register as a subcontractor
A "subcontractor" is anyone who carries out construction work for a contractor. This includes:
- Sole traders
- Partnerships
- Limited companies
- Self-employed labour-only
Effect of not registering: 30% rate instead of 20%. Substantial cash flow penalty.
Registration: HMRC online via Government Gateway. Need UTR (Unique Taxpayer Reference) and NI number.
Construction operations — what's in and out of scope
In scope:
- New build construction
- Repairs and refurbishment
- Demolition
- Internal alterations
- External works (paving, fencing, landscaping)
- Roofing
- Plumbing, electrical, decorating
- Heating installation
- Painting
- Plastering
Out of scope:
- Manufacturing components (off-site)
- Surveying and design (when standalone)
- Carpet fitting (usually)
- Routine cleaning (not as part of construction)
- Manufactured plant maintenance (where plant is the asset, not the building fabric)
When in doubt, treat as in-scope — the penalty for under-deducting is far higher than the cost of over-deducting.
Monthly CIS return — the operational rhythm
Each month the contractor must:
- Calculate deductions for each subbie payment in the tax month (6th to 5th)
- Submit CIS300 return by 19th of next month (paper) or 22nd (electronic)
- Pay deductions to HMRC by 19th (post) or 22nd (electronic) of the next month
- Issue payment and deduction statements to each subbie within 14 days of tax month end
Even nil returns must be submitted — if no subcontractor payments in the month, file a nil return. Failure produces £100 immediate penalty.
Verification — required before first payment
Before the first payment to any subcontractor in any tax year, the contractor must verify the subbie's status with HMRC:
- Subbie's name
- UTR
- NI number (sole trader/partnership) or Company Registration (Ltd)
- HMRC returns: confirmed subbie's status and rate (0%, 20% or 30%)
Verification is valid for 12 months. Re-verify if status changes. Failure to verify means automatic 30% deduction rate must apply.
Materials vs labour — the deduction calculation
CIS deduction applies to the labour element of each invoice/payment, not to materials, plant hire passed at cost, or VAT.
Example invoice:
- Labour: £2,000
- Materials: £600
- Plant hire: £150
- Total: £2,750
- VAT (where applicable): £550 (20% on £2,750)
- Total invoice: £3,300
CIS deduction (20% on labour only):
- 20% of £2,000 = £400 deducted
- Subbie receives: £3,300 - £400 = £2,900
- Contractor pays HMRC: £400
Materials and plant are not deducted. Subbies must itemise to avoid over-deduction. A bundled "labour and materials £2,750" invoice without breakdown will trigger 20% deduction on £2,750 = £550 deducted, costing the subbie cash flow.
Reverse charge VAT — separate but related
From 1 March 2021, the VAT reverse charge for construction services applies to most CIS supplies between VAT-registered businesses. Effect:
- Subbie does not charge VAT on the invoice
- Contractor accounts for both input and output VAT on their return
- VAT cash flow shifts from subbie to contractor
The reverse charge is a separate scheme from CIS but affects the same invoices. CIS deduction calculation is on the net (pre-VAT) labour element.
Gross Payment Status (GPS) — getting paid in full
GPS allows a subbie to be paid gross (no deduction). Eligibility:
- Business test — bank account in business name; UK construction trade
- Turnover test — labour turnover of £30,000+ (sole trader), £30,000 × partners (partnership), £30,000 × relevant persons (company)
- Compliance test — clean PAYE/SA filing history with HMRC, no significant non-compliance for 12 months
Apply via HMRC. Approval process 4–8 weeks. Annual review by HMRC; non-compliance can lose GPS.
For larger subbies with significant cash flow exposure, GPS is worth pursuing.
Penalties for non-compliance
- Late or missing CIS300 return — £100 immediate, £200 after 2 months, £300 or 5% of deductions (higher) after 6 months, further escalation
- Failure to verify subbies — penalties up to £3,000 per error
- Wrong deduction rate — recovery of unpaid tax + interest + penalty
- Failure to register as contractor — penalty up to £3,000
HMRC enforces CIS aggressively. A small builder paying £1,000/month to subbies without filing returns can rack up £3,000+ in penalties within a year.
Frequently Asked Questions
Do I need to register for CIS as a sole trader?
If you carry out construction work for a contractor, yes — registering avoids the 30% rate and gives you the standard 20% rate. Registration is free and online via Government Gateway.
What's the difference between CIS and PAYE?
CIS applies to self-employed subcontractors. PAYE applies to employees. The legal test for employee vs subcontractor is HMRC's status determination (using IR35-type criteria). Misclassifying an employee as a subcontractor produces serious tax and employment-law liability.
Can I claim back CIS deductions?
Yes. As a sole trader, the deductions count against your year-end Self Assessment tax bill. As a limited company, against your Corporation Tax. Most subbies receive a refund at year end if their CIS deductions exceed their actual tax liability.
Do I have to pay CIS on materials?
No. Materials, plant hire (passed through at cost), and VAT are excluded from CIS deduction. Only the labour element of an invoice is deducted.
Is private domestic work covered by CIS?
No. CIS covers payments by contractors to subcontractors. A homeowner paying a builder directly is not a contractor for CIS purposes. The builder, however, paying their own subcontractors, is a contractor under CIS.
Regulations & Standards
Finance Act 2004 — primary CIS legislation
Income Tax (Construction Industry Scheme) Regulations 2005 — operational regulations
CISR Manual (HMRC internal manual) — full guidance for HMRC officers
CIS Reverse Charge VAT Order 2019 — VAT reverse charge from March 2021
Self Employment / Employment Status Indicator (HMRC) — distinguishes self-employed from employed status
Construction (Design and Management) Regulations 2015 — separate but parallel safety legislation
The Income Tax (Pay As You Earn) Regulations 2003 — PAYE legislation (when subbies are reclassified as employees)
HMRC CIS guidance — official UK government guidance
CIS for contractors — contractor obligations
CIS for subcontractors — subcontractor obligations
VAT reverse charge for construction services — March 2021 reverse charge guidance
HMRC Status Indicator — employed vs self-employed classification