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    TaxKilnUK tax guidance
    TaxKilnUK tax guidance

    Being an employer → CIS for contractors

    CIS for Construction Contractors — Verification + 20%/30%/0% Deductions

    The Construction Industry Scheme (CIS) governs payments from contractors to subcontractors in construction work. Contractors must register with HMRC, verify each subcontractor's CIS status before paying, and deduct tax at source: 20% if verified, 30% if unverified, 0% for Gross Payment Status holders. Deductions are remitted to HMRC monthly via the CIS300 return by the 19th of the following month. From 1 March 2021, the CIS + VAT reverse charge (VAT Notice 735) shifted VAT accounting on most B2B construction supplies to the customer. CIS is a separate scheme to PAYE — but misclassifying an employee as a CIS subcontractor exposes the contractor to back-PAYE + NIC + penalties.

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    Guidance, not advice. We explain the rules, we don't assess your situation. Always seek financial or tax advice from your accountant, or contact HMRC. Read our editorial scope →

    In plain English

    If you operate in construction and pay subcontractors (not employees) for construction operations, you're a 'contractor' for CIS. Register with HMRC. For each subcontractor, before the first payment: verify their status online — HMRC tells you 20%, 30%, or 0% (Gross). Deduct accordingly from the labour element of each payment (materials, plant hire, VAT excluded from deduction base). File CIS300 monthly by the 19th, listing every subcontractor paid and the deduction made. Pay deducted amounts to HMRC by 22nd (electronic). Give each subcontractor a written CIS payment + deduction statement within 14 days of month-end. Gross Payment Status (GPS): subcontractors can apply. Tests: business test (operating in UK construction), turnover test (£30k/partner/director or £100k for company), compliance test (clean tax + filing record). HMRC reviews annually; revocation immediate on serious non-compliance. VAT reverse charge from 1 March 2021 (VAT Notice 735): for most B2B construction supplies between VAT-registered businesses where the customer is reporting under CIS, the supplier does NOT charge VAT. The customer accounts for both output VAT and equivalent input VAT — net cashflow neutral but eliminates missing-trader fraud. End users (customers not making onward supply) outside the regime. Critical trap: misclassifying an employee as a CIS subcontractor. If HMRC determines the relationship was actually employment (mutuality + control + personal service), the contractor faces back-PAYE + NIC + Class 1A on benefits + penalties for several years. CIS does not insulate against employment status determination.

    How it works

    Who is a contractor

    Mainstream contractor: business whose work is construction operations. Deemed contractor: non-construction business whose construction spend exceeds £3m over 12 months (reformed from old 'average £1m/year over 3 years' test in 2021). Either way, must register + verify + deduct + report.

    Construction operations covered

    Site preparation; demolition; building; alteration; repair; extension; installation of fittings; painting + decorating; cleaning the interior of a building forming part of construction. NOT covered: professional services (architects, surveyors); manufacture of building materials off-site; carpet fitting; scaffolding hire (without labour); installation of seating/blinds/shutters.

    Verification

    Online HMRC verification before first payment. Provide subcontractor's UTR + NI number / company name + UTR. HMRC returns status: registered with standard deduction (20%); registered with Gross Payment Status (0%); unmatched/unverified (30%).

    Deduction calculation

    Apply deduction rate to gross labour amount. Exclude: materials (with supplier evidence); plant hire (without operator); VAT; CITB levy; consumable stores. Example: £10,000 invoice = £7,000 labour + £2,500 materials + £500 plant. Deduction at 20% = £7,000 × 20% = £1,400. Pay subcontractor £10,000 − £1,400 = £8,600 plus give CIS statement showing £1,400 deduction.

    CIS300 monthly return + payment

    By 19th of following tax month: file CIS300 listing every subcontractor + payment + deduction. By 22nd (electronic): pay deductions to HMRC. Same Accounts Office reference as PAYE. Penalty for late CIS300: £100 immediate + escalating up to £3,000 + tax-geared.

    VAT reverse charge

    From 1 March 2021 (VAT Notice 735): B2B construction supplies between VAT-registered businesses where the customer reports under CIS — supplier issues VAT-exclusive invoice noting 'reverse charge' wording; customer accounts for output + input VAT on its own return. End users (last consumer in chain) outside scope. Mixed supplies: reverse charge applies to whole supply if any element falls within scope.

    Misclassification trap

    Engaging someone as a 'CIS subcontractor' who, under employment status tests, is really an employee = back-PAYE + NIC for several years + penalties. CIS does NOT override employment status. Use CEST + status determination + written terms (not just to evidence — to match reality, per Autoclenz).

    Who this applies to + key conditions

    Statute + manual references

    Primary: Finance Act 2004 Part 3 Chapter 3 + Income Tax (Construction Industry Scheme) Regulations 2005 (SI 2005/2045).

    Related: VAT Notice 735 — Construction Industry domestic reverse charge from 1 March 2021; Value Added Tax (Section 55A) (Specified Services and Excepted Supplies) Order 2019 (SI 2019/892); FA 2021 — CIS reform (deemed contractor rules + deductible materials clarification); ITEPA 2003 + employment status case law (Ready Mixed Concrete, Hall v Lorimer, etc) — for misclassification risk

    HMRC manual: Construction Industry Scheme Reform Manual (CISR); VAT Notice 735

    Common mistakes + traps

    Worked example

    Iota Construction Ltd, mainstream contractor, pays subcontractor Joe £10k (verified 20% deduction)

    Iota pays Joe a £10,000 invoice in June 2025: £7,000 labour + £2,500 materials (with receipts) + £500 plant hire (no operator). VAT registered both sides.

    1. Step 1 — Verify Joe before first payment: HMRC returns 'registered, standard deduction 20%'.
    2. Step 2 — Identify deductible element: labour only = £7,000.
    3. Step 3 — Calculate deduction: £7,000 × 20% = £1,400.
    4. Step 4 — VAT: reverse charge applies (B2B + Joe will use Iota's supply onward as CIS reportable). Joe issues invoice net of VAT with 'reverse charge' wording; Iota accounts for output + input VAT on its own VAT return.
    5. Step 5 — Pay Joe: £10,000 − £1,400 CIS deduction = £8,600 (no VAT element transferred).
    6. Step 6 — Issue CIS payment + deduction statement to Joe within 14 days of month-end.
    7. Step 7 — File CIS300 for June 2025 by 19 July 2025 listing the £10,000 / £1,400 deduction.
    8. Step 8 — Pay £1,400 to HMRC by 22 July 2025 (electronic).
    9. Step 9 — Joe reclaims £1,400 via Self Assessment (sole trader) or via CT600 + EPS offset (if Ltd subcontractor with own PAYE scheme).

    Outcome: Iota correctly deducts £1,400 on labour only, files CIS300 on time, applies VAT reverse charge, gives Joe paperwork to reclaim. Joe receives £8,600 net.

    How this connects to the rest of the framework

    Becoming an employer + PAYE registration →

    CIS is a separate scheme to PAYE — but both may apply if you have employees AND subcontractors.

    RTI mechanics →

    Subcontractors deducted from suffer CIS via EPS as a reduction in monthly PAYE/NIC liability.

    Employee vs worker vs self-employed →

    Misclassifying an employee as a CIS subcontractor exposes contractor to back-PAYE.

    /tax-reliefs-uk/cis-refund →

    Subcontractors who overpaid via CIS deductions can reclaim via Self Assessment / CT600.

    Frequently asked questions

    What happens if I miss the Self Assessment deadline?+
    The Self Assessment deadline is 31 January (online filing) for the previous tax year. Miss it and HMRC apply an automatic £100 penalty. Beyond that: £10 per day from 3 months late (capped at £900), 5% of tax due at 6 months late, and another 5% at 12 months late, under Schedule 55 of the Taxes Management Act 1970. If you have a genuine reason (serious illness, bereavement, technical issue with HMRC's systems) you can appeal with evidence; HMRC accepts reasonable excuse appeals in most genuine cases.
    Do I need an accountant or can I file Self Assessment myself?+
    Legally you can file Self Assessment yourself via gov.uk for free, most simple sole-trader returns (single income source, basic expenses) are realistic to self-file. An accountant adds real value when: your trading profit is above £40,000 (extraction-strategy decisions matter), you have multiple income streams (PAYE + self-employment + property + dividends), you've crossed the £90,000 VAT threshold, you're considering incorporation, or you have an HMRC enquiry. Expect to pay £400-£1,500/year for a typical sole-trader accountant; the cost is itself a deductible expense.
    How do payments on account work?+
    When your Self Assessment tax bill exceeds £1,000 for the first time, HMRC requires payments on account toward NEXT year's tax. Half the current bill is due 31 January (alongside the current bill); the other half is due 31 July. So your first January after crossing the threshold can hit with a double-bill: last year's balance + first payment on account. Adjust via Form SA303 if you expect next year's income to drop substantially. Payments on account don't apply if more than 80% of your tax is collected via PAYE.
    What are the CIS deduction rates?+
    20% (subcontractor verified registered), 30% (unverified or unmatched), 0% (Gross Payment Status holder). Always verify before first payment.
    Does CIS apply to VAT?+
    No — VAT is excluded from the deduction base. Separately, the CIS + VAT reverse charge from 1 March 2021 changes how VAT is accounted on B2B construction supplies.
    When does deemed contractor status arise?+
    When a non-construction business's construction spend exceeds £3m over 12 months (reformed 2021 from the older average £1m/3-year test).
    Can CIS subcontractors be employees?+
    Status is determined by the reality of the working relationship (Autoclenz v Belcher [2011] UKSC 41). CIS registration does NOT override employment status. Misclassifying an employee = back-PAYE + NIC exposure.

    Free + regulated-body resources

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