Construction Industry Scheme (CIS) Explained for Tradespeople
Quick Answer: CIS is an HMRC tax scheme requiring contractors to deduct 20% (verified) or 30% (unverified) from payments to subcontractors and pass it to HMRC. These deductions are not a separate tax — they are credited against the subcontractor's income tax and National Insurance bill at the end of the tax year. Contractors must register, verify subcontractors before first payment, and submit monthly CIS300 returns by the 19th of each month.
Summary
The Construction Industry Scheme has been part of the UK tax landscape since the Finance Act 1971, substantially reformed by the Finance Act 2004. It was introduced because the construction industry has historically had high rates of tax evasion — workers paid cash in hand, subcontractors disappearing without paying tax. CIS is HMRC's mechanism to ensure tax is collected at source before money flows through the supply chain.
Under CIS, contractors withhold a percentage of payments to subcontractors and send it directly to HMRC. The subcontractor is not losing money — they get a credit for those deductions when they file their Self Assessment or corporation tax return. If deductions exceed their tax liability, they receive a refund. The scheme therefore works like PAYE but for self-employed people in construction: tax is collected upfront, reconciled annually.
Understanding whether you are a contractor, a subcontractor, or both — and knowing your obligations in each role — is essential. Getting it wrong exposes you to penalties, back-dated deductions, and interest charges. HMRC has actively increased compliance activity in the construction sector, including via Real Time Information crosschecks with PAYE records.
Key Facts
- Governing legislation — Finance Act 2004, Sections 57–77; Income Tax (Construction Industry Scheme) Regulations 2005
- Who administers it — HMRC; all interactions through Government Gateway (online)
- Contractor definition — any business paying subcontractors for construction work, OR any business spending more than £1 million per year on construction (even non-construction businesses such as property developers, supermarkets, or housing associations)
- Subcontractor definition — any individual or company receiving payment from a contractor for construction work
- Deduction rates — 20% for verified registered subcontractors; 30% for unverified or unregistered subcontractors; 0% for those with gross payment status
- Gross payment status — available if turnover exceeds £30,000/year (sole trader), £100,000/year (company), and HMRC compliance record is clean
- Monthly return deadline — CIS300 must reach HMRC by 19th of the month following the tax month in which payments were made
- Payment statement — subcontractors must receive a written statement each month showing gross amount, deductions made, and net paid
- Materials excluded from deductions — CIS applies to the labour element only; materials (at cost price) are excluded from the CIS calculation
- Verification — contractors must verify every subcontractor with HMRC before making the first payment
- Penalties for late filing — £100 for up to 2 months late; £200 for 2–6 months; £300 or 5% of deductions (whichever is higher) for 6–12 months; up to £3,000 for over 12 months
- Both contractor and subcontractor — many tradespeople are simultaneously contractors (paying subbies) and subcontractors (working for a main contractor); both sets of obligations apply
- Employment status — CIS does not override employment status rules; if a subcontractor is actually an employee, PAYE applies regardless
- End of year reconciliation — deductions suffered are reported on Self Assessment (sole traders) or corporation tax return (companies) and offset against liability
Quick Reference Table
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Try squote free →| Subcontractor Status | Deduction Rate | Who It Applies To |
|---|---|---|
| Gross payment status | 0% | Turnover >£30k/yr (sole trader) or >£100k/yr (company); clean compliance record |
| Registered and verified | 20% | Registered with HMRC CIS, verified by contractor |
| Unregistered or unverified | 30% | Not registered with HMRC CIS, or contractor could not verify |
| Role | Key Obligation | Deadline |
|---|---|---|
| Contractor | Verify subcontractors | Before first payment |
| Contractor | Submit CIS300 return | 19th of following month |
| Contractor | Issue payment statements | Monthly |
| Contractor | Pay deductions to HMRC | 19th of following month (22nd electronic) |
| Subcontractor | Register with HMRC CIS | Before work starts (to get 20% not 30%) |
| Subcontractor | Claim deductions on tax return | Annual Self Assessment / corporation tax |
Detailed Guidance
Who Is a Contractor Under CIS?
The contractor definition is wider than most people expect. You are a CIS contractor if:
- You pay subcontractors for construction work — regardless of your business size or whether construction is your primary activity; or
- Your business spends more than £1 million per year on construction in any three-year period — this catches businesses that are not themselves in construction: property companies, large retailers, local authorities, and housing associations routinely fall within this definition.
If you are a contractor, you must register for CIS with HMRC before making any payments to subcontractors for construction work.
Who Is a Subcontractor Under CIS?
You are a CIS subcontractor if you receive payment from a contractor for construction operations. This includes:
- Sole traders working for a main contractor
- Limited companies engaged as subbies
- Partnerships taking on subcontract work
Most trades working up the supply chain (rather than directly for end clients) will be subcontractors for at least some of their income.
What Counts as Construction Work?
CIS applies to "construction operations" as defined in the Finance Act 2004. The definition is broad:
Included: New build construction, extensions, alterations, repairs and maintenance, groundworks, site preparation, demolition, roofing, plumbing, heating, gas work, electrical installation, plastering, painting and decorating, tiling, flooring, carpentry and joinery, brickwork, scaffolding, and equipment hire where the hirer also provides operators.
Excluded: Professional services (architects, surveyors, engineers, project managers), delivery of materials only (no installation), manufacture of components off-site (unless installation is also done), and work on property you own.
CIS does not apply to services that are ancillary to construction but not construction themselves — a security guard on a site is not doing construction work; a plant operator is.
The Verification Process
Before making the first payment to any subcontractor, a contractor must verify them with HMRC. Verification tells the contractor what rate to apply.
Verification can be done:
- Online via HMRC Government Gateway
- By telephone (HMRC CIS Helpline: 0300 200 3210)
- Through payroll software that supports CIS
You will need the subcontractor's:
- Full name (or company name)
- UTR (Unique Taxpayer Reference)
- National Insurance number (for individuals)
- Company registration number (for limited companies)
HMRC will confirm whether the subcontractor is registered and at which rate. Keep a record of every verification — date, method, and the reference number HMRC provides. This protects you if the rate is later disputed.
Verification numbers are not permanent. If you have not paid a subcontractor for two years, you must re-verify before resuming payments.
How CIS Deductions Work in Practice
Once verified, the deduction is applied to the labour element only of each payment. Materials are excluded.
Example: A plumber invoices a main contractor:
- Labour: £1,000
- Materials (pipes, fittings): £300
- Total invoice: £1,300
CIS deduction (20% on labour only): £200
Payment to the plumber: £1,100 (£1,300 – £200)
The contractor pays £200 to HMRC on the plumber's behalf. The plumber records £200 as a deduction suffered, and offsets it against their tax bill at year-end.
The materials figure must represent the actual cost of materials — it should not be inflated to reduce the CIS liability. HMRC scrutinises materials claims, and if materials are found to be overstated, the deduction should have been higher.
Monthly CIS300 Returns
Contractors must submit a CIS300 return to HMRC by the 19th of the month following each tax month. Tax months run from the 6th to the 5th (e.g. 6 March to 5 April).
The return records:
- Each subcontractor paid during the month
- Gross amount paid (before deduction)
- Materials element (excluded from deduction)
- Amount deducted
Payment of deductions to HMRC is due by the same date (19th by post/cheque; 22nd if paying electronically).
Nil returns must still be filed if you are registered as a contractor but made no payments in a month. You can request an exemption from monthly filing if you expect to have no payments for a period.
Late filing penalties start at £100 per return and escalate rapidly with time. HMRC can also issue penalties for inaccurate returns.
Gross Payment Status: Getting Your Full Pay Upfront
Gross payment status (GPS) means a contractor pays you in full with no CIS deduction. This improves cashflow significantly — you receive 100% of your invoice and settle your tax through Self Assessment at year-end rather than having 20% withheld throughout the year.
Eligibility criteria:
- Turnover test: net construction turnover of at least £30,000/year for a sole trader (£100,000/year for a company, £200,000/year if the company has multiple shareholders)
- Compliance test: all tax returns and payments must be up to date across all taxes (income tax, VAT, PAYE, CIS as a contractor if applicable)
- Business test: the business is genuinely carrying on construction operations
Apply via the Government Gateway. HMRC will check the compliance record going back typically 12 months. If the record is clean, GPS is granted. HMRC reviews GPS periodically — if compliance slips, GPS can be withdrawn.
How Subcontractors Reclaim CIS Deductions
Deductions suffered are not lost. They are credited against your tax liability.
Sole traders: Complete the CIS section of your Self Assessment return. Enter total deductions suffered during the tax year. HMRC credits these against your income tax and Class 4 NIC bill. If deductions exceed your liability, HMRC refunds the difference — often within weeks of filing.
Limited companies: Deductions suffered are recorded on the company's corporation tax return. If deductions exceed the corporation tax liability, the company can also offset CIS deductions against PAYE/NIC due to HMRC. Companies must apply to set off CIS deductions against PAYE rather than waiting for a refund — there is a specific process for this via the PAYE online system.
CIS and VAT: The Domestic Reverse Charge
Since March 2021, VAT on most construction services supplied between VAT-registered contractors and subcontractors is handled via the Domestic Reverse Charge (DRC). Under DRC, the subcontractor does not charge VAT on their invoice — the contractor accounts for VAT directly to HMRC.
CIS and DRC are separate mechanisms but interact: if DRC applies to a supply, CIS deductions are calculated on the net amount (excluding VAT, as no VAT is charged by the sub). The two schemes operate alongside each other and both obligations must be met.
Frequently Asked Questions
I am a sole trader working for domestic clients directly. Do I need to register for CIS?
If you only work directly for domestic homeowners, CIS generally does not apply — homeowners are not contractors for CIS purposes. You need to register as a subcontractor if you work for a contractor who will need to deduct CIS from your payments, and as a contractor if you pay other subcontractors for construction work.
What if the contractor deducts the wrong amount?
If too much is deducted, you claim the excess back through your tax return. If too little is deducted, HMRC will pursue the contractor (not you as the subcontractor) for the shortfall. Keep your payment statements and reconcile them against what you receive.
Can a limited company claim gross payment status?
Yes, but the turnover threshold is higher (£100,000 for a single director company). The company's compliance record — including PAYE, VAT, and corporation tax submissions — must all be clean.
What happens if a contractor fails to deduct CIS?
The contractor is liable to HMRC for the uncollected deduction. HMRC may also pursue penalties. Being paid gross when the correct rate is 20% or 30% is the contractor's problem — the subcontractor still owes the underlying tax, but HMRC's immediate enforcement action targets the contractor who failed to deduct.
Are CIS deductions the same as tax?
No. They are a payment on account of the subcontractor's eventual tax liability. The actual tax is calculated on the annual tax return. CIS deductions are credits towards that liability, not a separate tax.
Regulations & Standards
Finance Act 2004, Sections 57–77 — primary legislation establishing CIS
Income Tax (Construction Industry Scheme) Regulations 2005 — detailed procedural rules covering verification, returns, and payment statements
Finance Act 2021 — introduced changes to GPS compliance conditions
HMRC CIS Guide (CIS340) — HMRC's detailed operational guidance for contractors and subcontractors
VAT Notice 735 — HMRC guidance on the Domestic Reverse Charge for construction services
HMRC: VAT Domestic Reverse Charge for Building and Construction
Sole trader vs limited company — how your business structure affects CIS obligations, thresholds, and gross payment status eligibility
VAT for tradespeople — the Domestic Reverse Charge works alongside CIS and both must be applied correctly
Managing subcontractors on site — practical guidance on engaging subbies, including CIS verification and payment statement obligations
Self Assessment for tradespeople — how to claim CIS deductions suffered on your annual tax return