Construction business expenses in the UK: the complete guide for builders, contractors and subbies

Construction is the one UK sector with its own tax machinery bolted on top of the normal expense rules. Before a builder thinks about materials, tools or the van, the Construction Industry Scheme and the VAT domestic reverse charge have already changed how cash moves between contractor and subcontractor and how every invoice must be written. Get those two right, add the VAT rates that depend on what you are building, and the rest is ordinary bookkeeping done at volume. This guide goes through the whole ledger of a UK builder, contractor or subcontractor, category by category, with a verdict for each one before the detail. Every figure is sourced to HMRC or GOV.UK in the Sources section, retrieved 10 October 2026.

What this guide covers: CIS deductions and returns, the VAT reverse charge, VAT rates on building work, materials and consumables, tools, plant and the Annual Investment Allowance, vans and the van benefit, mileage, wages, National Insurance and pensions, protective clothing and workwear, repairs, insurance and fines, and the records, VAT returns and year-end work that tie it together.

The construction ledger at a glance

The rest of this guide walks through each row, and every section opens with its verdict.

Where ExpenseFlow fits

The construction load is documentary: every subbie invoice needs its labour and materials split for CIS, its VAT treatment confirmed for the reverse charge, and its receipt kept for six years. ExpenseFlow captures each receipt and supplier invoice (email forward, upload or phone), reads the line items and the VAT, codes each line to your chart of accounts with a written reason, and routes anything uncertain to a person before it posts. For UK construction the checks that matter are built in: a construction-service line still charged at standard 20% VAT is flagged as a possible domestic reverse charge; a VAT rate that is not a valid UK rate is flagged; a capital purchase is flagged for the capital allowances route rather than expensed; and the line-level VAT is recomputed against the printed totals. After approval the bill syncs to Xero, whose UK edition calculates the CIS deduction on subcontractor bills and files the monthly return, with the source document attached, or to QuickBooks Online as a coded bill.

What it does not do: it does not verify subcontractors with HMRC, it does not decide whether a customer is an end user, it does not run payroll, and it does not file the CIS return or the VAT return. Those stay with you, your software and your accountant. The construction chart of accounts for Xero and for QuickBooks line up with the categories below.

The ExpenseFlow for construction and trade businesses page covers these checks across all five countries.

CIS: deductions and the monthly return

Under the Construction Industry Scheme a contractor deducts money from a subcontractor’s payment and pays it to HMRC as an advance toward the subcontractor’s tax and National Insurance ^[1] . The rate is 20% for registered subcontractors, 30% for unregistered subcontractors and 0% for those with gross payment status ^[1] . The deduction is not taken from the whole invoice: start from the gross amount and subtract VAT and the costs the subcontractor paid for, namely materials, consumable stores, plant hire, fuel other than for travel, and manufacturing or prefabricating materials, then apply the rate to the remainder ^[1] .

The monthly return goes to HMRC by the 19th of the month following the tax month: a return covering 6 May to 5 June is due by 19 June ^[2] . It declares that the subcontractors listed are not employees, and a month with no payments still needs a nil return or an inactivity request ^[2] . Late returns cost £100 at one day, £200 at two months, and £300 or 5% of the deductions at six months, whichever is greater ^[2] . Xero’s UK edition holds each subcontractor’s deduction rate on the contact, applies the deduction on the bill, sends the return to HMRC and emails the statements ^[13] ; the contractor payments in Xero guide walks the setup.

The VAT domestic reverse charge

Since 1 March 2021 the domestic reverse charge must be used for most standard and reduced rated building and construction services supplied between businesses registered for VAT in the UK and reported within CIS ^[3] . Some services are outside it when supplied on their own, such as architects’ and surveyors’ professional services and installing security systems, and those follow normal VAT rules ^[3] . The reverse charge does not apply to supplies to an end user, meaning a taxable person who uses the services for something other than making further supplies of construction services, when that end user tells the supplier or building contractor in writing that it is an end user ^[4] . Work for private householders is outside CIS and therefore outside the reverse charge.

The practical effect for subcontractors is cash flow: reverse-charged invoices stop carrying the 20% VAT that used to sit in the bank until the VAT return was due.

VAT rates on building work

HMRC’s VAT Notice 708 sets the rates. The construction of new qualifying dwellings and communal residential buildings, and certain new buildings used by charities, is zero-rated ^[5] . The renovation or alteration of empty residential premises, generally empty for at least two years, and qualifying residential conversions are charged at the reduced 5% rate ^[5] . Otherwise the construction of a new building and work to an existing building is normally standard-rated, though an extension that creates an additional dwelling can be zero-rated ^[5] . Register for VAT once your taxable turnover passes £90,000 over the last 12 months ^[12] ; the UK VAT and Making Tax Digital guide and the VAT return guide cover the return.

Materials and consumables

Timber, blocks, plaster, pipe, cable, fixings, adhesives and blades are ordinary costs of the work. Reclaim the VAT shown on the merchant’s VAT invoice; a builders’ merchant docket usually qualifies, a card slip does not. Materials on a subbie’s invoice are their cost, not yours, which is why the CIS deduction base excludes them ^[1] ; when HMRC checks a contractor, the subbie’s receipted materials are what supports paying that part gross.

Tools, plant and the Annual Investment Allowance

The Annual Investment Allowance gives relief on most plant and machinery up to £1 million a year, for sole traders, partnerships and companies, and business cars are excluded and claim writing-down allowances instead ^[6] . Hand and power tools, generators, mixers, scaffolding, excavators and vans all sit inside it. Hired plant is an ordinary running cost with reclaimable VAT. The equipment and tools guides set out the pools, and the capital allowance glossary entry the mechanics.

Vans, cars and the van benefit

If a van is used only for business there is nothing to report, and private use that is insignificant, such as a small detour to buy a paper on the way to work, is also exempt ^[7] . Pool vans used by more than one employee, available because they need it for the job, not normally kept at home and used only for business journeys are exempt too ^[7] . Where private use goes further, the van benefit charge is £4,170 and the van fuel benefit charge £798, and zero-emission vans are reported at 0% ^[8] . A van is plant for the Annual Investment Allowance; a car is not ^[6] . The vehicle guide covers the car side.

Mileage and travel

From 6 April 2026 the approved mileage rate for cars and vans is 55p a business mile for the first 10,000 miles and 25p after, with 24p for motorcycles and 20p for bicycles; payments above the approved amount go on form P11D ^[9] . Travel between sites, and to a temporary workplace, is business travel; the mileage and travel guides carry the temporary workplace rules and the mileage log template the record.

Wages, National Insurance and pensions

From 1 April 2026 the National Living Wage is £12.71 an hour for workers aged 21 and over, £10.85 for 18 to 20 and £8.00 for under 18s and apprentices ^[10] . Employer Class 1 National Insurance is 15% above the secondary threshold of £96 a week in 2026-27 ^[11] , eligible employers reduce it by up to £10,500 a year through the Employment Allowance ^[14] , and automatic enrolment adds a minimum 3% employer contribution on qualifying earnings ^[15] . The CIS return itself makes you declare that the subcontractors listed are not employees, and a wrong declaration can cost up to £3,000 ^[2] .

Protective clothing and workwear

Employers do not pay tax or National Insurance on most uniforms or protective clothing they provide ^[16] . Employees can claim relief for cleaning, repairing or replacing a uniform or specialist clothing such as safety boots, but not the initial cost of work clothing and not everyday clothing even if a colour is required ^[17] . Boots, hi-vis, hard hats, gloves and eye protection bought by the business are ordinary costs with reclaimable VAT.

Repairs, insurance, fines and the small stuff

Repairing a mixer or replacing a worn part keeps an asset in its existing state and is a running cost; upgrading a machine beyond what it was is capital. Public liability, employer’s liability, contract works and tool insurance are deductible and carry no VAT. Phone, software, accountancy, trade association fees and skip hire are ordinary costs. Fines and penalties, CIS late filing penalties included ^[2] , are not deductible.

Records, returns and year end

Business records are kept for six years, as the record-keeping guide sets out. For CIS keep each subcontractor’s verification, the monthly returns and the payment and deduction statements; for the reverse charge keep any end-user notification with your VAT records. The tax deadlines calendar has the CIS, VAT and PAYE dates, and the year-end checklist walks the close.

Common mistakes

• Taking the CIS deduction from the whole invoice instead of the labour element ^[1] .
• Filing the CIS return after the 19th, or skipping the nil return ^[2] .
• Charging 20% VAT on a reverse-charge job, or reverse-charging an end user who notified you in writing ^{[3] [4]} .
• Charging 20% on a new dwelling that is zero-rated, or zero on repairs that are standard-rated ^[5] .
• Treating a van purchase as a running cost and missing the Annual Investment Allowance ^[6] .
• Letting workers use the van at weekends without reporting the van benefit ^{[7] [8]} .
• Declaring a labour-only worker as a subcontractor when they are an employee ^[2] .
• Paying mileage above 55p without reporting the excess ^[9] .
• Reclaiming VAT on insurance, which carries none.