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    Tax for UK builders

    UK builders typically operate as Ltd companies for limited liability against site-accident + defects litigation. CIS dominates the tax landscape, both as a contractor verifying + deducting from subcontractors (20% registered / 30% unregistered / 0% gross status) and as a subcontractor reclaiming deductions via CT600 or Self Assessment. The construction VAT reverse charge applies on inter-business supplies in the CIS chain since 1 March 2021, and the Annual Investment Allowance of £1,000,000 covers second-hand plant (diggers, dumpers, telehandlers) at 100% relief in the year of purchase.

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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 →

    UK builders and general construction trades operate as sole traders or, more commonly, Ltd companies (for limited liability protection on site-accident and defects-litigation risk). CIS dominates the tax landscape, both as a contractor paying subcontractors and as a subcontractor receiving deductions. The VAT reverse charge applies on construction services to other VAT-registered businesses in the supply chain. Capital allowances cover heavy plant, mini-diggers, dumpers, scaffolding, under AIA.

    What business structure do builders use?

    The common patterns for builders are: Sole trader, only for solo trades with low liability exposure (e.g. solo joinery), Ltd Co (most common), limited liability for site-accident + defects litigation; better for landing larger commercial contracts, Subcontractor under main builder Ltd Co, common early-career or specialist (e.g. bricklayer subcontracting to a developer). The right structure depends on revenue, liability exposure, and personal circumstances, covered below.

    How does CIS apply to builders?

    builders working as subcontractors on construction projects fall inside the Construction Industry Scheme. See the dedicated CIS mechanics below.

    How does CIS work for builders (both as contractor + subcontractor)?

    Builders are often BOTH a contractor (hiring subbies) AND a subcontractor (working under a main contractor). Both roles have CIS obligations. As contractor: you must verify each subcontractor's CIS status with HMRC before paying them, deduct CIS at the right rate (30% unregistered / 20% registered / 0% gross status), pay the deduction to HMRC by 22nd of the following month, issue a payment + deduction statement to the subcontractor, and file CIS monthly return CIS300. As subcontractor: a main contractor will deduct CIS from your payments. Reclaim via Self Assessment (sole trader) or via Ltd Co CT600 + PAYE setoff (Ltd Co). Aim for gross payment status as early as possible, the £30,000 turnover test is achievable in the first 12 months. Common trap: failing to register as a contractor when you first hire a subbie. The moment you pay a labour-only subcontractor for construction work, you ARE a contractor under CIS, even if it's a one-off. Register before the first payment.

    CIS contractor + subcontractor obligations apply to all construction operations, contractors must verify, deduct, report; subcontractors reclaim deductions via SA or CT600. (Finance Act 2004 sections 57-77 + Income Tax (Construction Industry Scheme) Regulations 2005; HMRC manual CISR43260)

    How does the VAT reverse charge affect builders?

    Same mechanics as plumbers + electricians: VAT-registered builder invoicing another VAT-registered construction business does NOT charge VAT, the customer accounts for it under reverse charge. Invoice must show 'Reverse charge: customer to pay the VAT to HMRC'. Builder-specific scenarios: New-build housing: developer's supply to end-user buyer is ZERO-rated. Builder's supply to developer is reverse-charged at the rate that would otherwise apply (zero-rated for the new-build dwelling component, standard 20% for any non-dwelling work). Complex projects often have mixed VAT treatment per phase. Refurb of existing dwelling: standard 20% VAT applies. Reverse charge applies if customer is VAT-registered construction business; standard VAT if customer is the householder. Conversion of non-residential to residential: reduced 5% VAT. Apply 5% even when reverse charging. Listed building work: was zero-rated pre-2012; standard 20% since. Common confusion area. End-user notification: a VAT-registered customer who is the end-user can notify you they are the end-user, in which case standard VAT applies. Get the notification in writing.

    VAT reverse charge for construction services applies to specified construction services in CIS supply chains where customer is VAT-registered and CIS-registered and not an end-user; rate that would otherwise apply (standard 20% / reduced 5% / zero-rated 0%) is what the customer accounts for. (VAT Act 1994 + The Value Added Tax (Section 55A) (Specified Services and Excepted Supplies) Order 2019; HMRC manual VAT Notice 735)

    What capital allowances apply to builders' plant and equipment?

    Builders have the heaviest capital allowance loads of any trade. AIA at £1,000,000/year covers most: mini-digger (£15-30k), dumper (£10-20k), telehandler (£25-50k), scaffolding system (£5-30k depending on scale), site tools + power tools + hand tools. Full Expensing (100% first-year relief for Ltd Cos on new plant) applies, particularly valuable for buying new yellow plant. Hire vs purchase: hire is a revenue expense (no capital allowance, just rental cost as deductible expense). Purchase is capital (AIA + WDA). For occasional-use plant (e.g. a mini-digger used 3 months/year), hire is usually cheaper than purchase even after tax relief. For continuous-use plant (e.g. a daily-driver dumper), purchase + AIA wins. Structures and Buildings Allowance (SBA): 3% straight-line on commercial buildings the company owns + uses for trade. For a builder owning their own yard + workshop, the SBA applies to the structural cost. Second-hand plant: AIA applies at full purchase price, no reduction for being used. Major opportunity to AIA-relieve a £40k second-hand telehandler in full.

    Annual Investment Allowance of £1,000,000 covers plant and machinery (new or second-hand) in year of purchase; Full Expensing provides 100% first-year relief for Ltd Cos on qualifying NEW plant. (Capital Allowances Act 2001 + Finance Act 2023 (Full Expensing); HMRC manual CA23122)

    What is the CITB Levy and does it apply to me?

    The Construction Industry Training Board (CITB) Levy is a payroll-based levy on construction employers above a payroll threshold. For 2025/26: levy applies to construction employers with PAYE-paid + CIS-paid payroll above £500,000/year (verify against current CITB threshold). Sub-threshold employers register with CITB but don't pay levy. Levy rate: 0.35% of PAYE payroll + 1.25% of CIS-paid subcontractor labour. Annual return + payment cycle. If you ARE levied, CITB offers training grants worth more than the levy paid in most cases, apprentice grants, course attendance grants, qualification grants. Most levied employers come out ahead net of grants claimed. Most small-trader Ltd Cos are below the £500k payroll threshold and don't pay levy, but should still register with CITB to access free training subsidies. Tax treatment: levy paid is a deductible business expense. Grants received are taxable trading income (not capital).

    CITB Levy applies to construction employers above £500,000 annual payroll threshold at 0.35% of PAYE payroll + 1.25% of CIS-paid subcontractor labour; deductible business expense; grants taxable as trading income. (Industrial Training Act 1982 + Industrial Training (Construction Board) Order)

    Allowable expenses

    Category Examples Tax treatment
    Heavy plant + tools Mini-digger, dumper, telehandler, scaffolding, power tools, hand tools, cordless drill sets, ladders Equipment AIA-eligible; consumable hand tools revenue expense
    Site PPE + clothing Hard hat, hi-vis, steel-toe boots, gloves, safety glasses, knee pads Revenue expense (pure PPE always allowable)
    Site insurance + JCT contracts Public + employer liability insurance (£5m minimum if employing), contract works insurance, JCT contract templates Revenue expense
    CSCS card + qualifications CSCS card renewal, NVQ Level 2/3 updates, SMSTS / SSSTS site management courses, F-Gas if HVAC crossover CPD revenue expense; initial qualifying NVQ NOT allowable
    Trade body subs Federation of Master Builders (FMB), National Federation of Builders (NFB), Guild of Master Craftsmen Revenue expense
    Vehicle + fuel Work van (Transit, Sprinter), pickup truck, fuel, servicing, tax, MOT Actual cost (Ltd Co) or simplified mileage 45p/25p (sole trader using own vehicle)
    Materials (cost-of-sale) Bricks, blocks, mortar, timber, plasterboard, insulation, roof tiles, purchased per job Cost of sale (input VAT recoverable if VAT-registered)
    Subcontractor payments Bricklayer subbies, scaffolder hire, electrician subbies (under CIS) Cost of sale; CIS deductions made + reported on CIS300; labour cost deductible
    Yard + workshop Commercial yard rental, workshop electricity, secure container storage Revenue expense; building structural cost = Structures and Buildings Allowance 3%

    Vehicle and travel costs

    Work van or pickup truck almost universal, actual cost method for Ltd Co company van with £4,020 BIK + £757 fuel BIK for personal use. Sole trader using own van uses simplified mileage 45p/25p. Specialist vehicles (tipper, low-loader for plant transport) are AIA-eligible commercial vehicles.

    Capital allowances and equipment

    A builder's typical heavy investment year: £40,000 second-hand telehandler + £8,000 used mini-digger + £12,000 scaffolding system + £5,000 new power tools = £65,000 capital expenditure. All AIA-relieved fully in year of purchase (well within £1m AIA ceiling). For a Ltd Co with £100,000 profit before capital allowances, this brings taxable profit to £35,000, saving £16,250 in Corporation Tax at 25% main rate (or less at small-profits rate). Cash-flow impact of timing capital purchases pre-year-end is significant.

    Worked example

    Hassan — Birmingham, England

    small Ltd Co construction firm (refurbs + new-build subcontracting) (2025/26)

    Ltd Co turnover 2025/26 £180,000 (mix of refurbs as main contractor + new-build subbie work). Materials £55,000. Subcontractor labour £35,000 (CIS-deducted at 20% on the registered subbies + 0% on the one with gross status). Van + plant running costs £12,000. Insurance + CITB registration + CSCS renewals + safety training £4,500. Salary to himself £12,570 + £30,000 dividend.

    Trading profit: revenue £180,000 - materials £55,000 - subbie labour £35,000 - van/plant £12,000 - insurance/admin £4,500 - director salary £12,570 = £60,930. Employer NI on director salary £12,570: above £5,000 ST = £7,570 × 15% = £1,136 Employer NI. Employment Allowance £10,500 covers, net Employer NI £0.

Corporation Tax: profit £60,930. Marginal relief applies, between £50,000 (SPR upper limit) and £250,000 (main rate lower limit). Marginal relief formula: (£250,000 - £60,930) × (£60,930 / £60,930) × 3/200 = £2,836. Tax at main rate 25%: £60,930 × 25% = £15,232. Less marginal relief: £15,232 - £2,836 = £12,396 CT due.

Dividend extraction: £30,000 dividend. Personal allowance £12,570 fully used by salary. Dividend allowance £500 = nil. Basic rate dividend tax 8.75% on remainder: (£30,000 - £500) × 8.75% = £2,581. Personal tax position: total income £42,570, below higher rate £50,270, so all dividends at basic.

CIS reconciliation: £35,000 subbie labour. 20% CIS deducted on registered subbies (assume £20,000 = £4,000 CIS deduction) paid to HMRC monthly. Hassan's own subbie work this year £0, no inbound CIS deductions to reclaim.

    Common HMRC audit triggers for builders

    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.
    When do I have to register as a CIS contractor?+
    The moment you make your first payment to a labour-only subcontractor for construction work, even a one-off. Register with HMRC before that first payment so you can verify the subcontractor's status and deduct at 20% rather than the 30% unregistered rate. Once registered, you must file a monthly CIS300 return (even nil returns), issue payment + deduction statements to subcontractors, and pay deductions to HMRC by the 22nd of the following month. Late or missed returns trigger automatic £100 penalties.
    Can I claim full tax relief on a second-hand telehandler or mini-digger?+
    Yes, the Annual Investment Allowance at £1,000,000 applies to second-hand plant at full purchase price with no reduction for being used. A £40,000 second-hand telehandler bought in 2025/26 is fully AIA-relieved in the year of purchase, saving up to £10,000 in Corporation Tax at the 25% main rate. Full Expensing (100% first-year relief for Ltd Cos) only applies to NEW plant, so for second-hand kit AIA is the route. Hired plant is a revenue expense, usually cheaper than purchase for occasional-use machines.
    Does the VAT reverse charge apply on a new-build house?+
    Yes, but with a twist. The developer's onward sale of a new-build dwelling to the end-buyer is zero-rated. Your supply as a subcontractor to that developer is reverse-charged at the rate that would otherwise apply, zero for the dwelling component, standard 20% for any non-dwelling work. Your invoice must show 'Reverse charge: customer to pay the VAT to HMRC' and the customer accounts for the VAT on their own return. Refurbishment of an existing dwelling is standard-rated 20%; conversion from non-residential to residential is reduced 5%.
    Do I have to pay the CITB Levy?+
    Only if your construction PAYE + CIS-paid payroll exceeds £500,000 a year. Below that threshold you should still register with CITB (it's free) so you can claim training subsidies, apprentice grants, course attendance grants, qualification grants, which often exceed any levy a small employer would have paid. Above the threshold the levy is 0.35% of PAYE payroll plus 1.25% of CIS-paid subcontractor labour, paid annually. The levy itself is a deductible business expense; grants received are taxable trading income.

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