CIS deductions and refunds, tool and van expenses, PPE, National Insurance, the VAT reverse charge and MTD explained for self-employed timber frame erectors.
Erecting timber frames is hard, physical, weather-dependent work, and the tax position reflects the trade you are actually in: you turn up on a new-build plot, take delivery of craned prefabricated panels, plumb and level them, fix them down, and move on to the next job. Most erectors do this as self-employed subcontractors working for one or more main contractors, which means two things dominate your tax life: the Construction Industry Scheme (CIS), and a genuinely long list of tools, plant-hire and travel costs that the CIS deduction completely ignores.
Get those two things right and the annual Self Assessment is usually good news rather than bad. This guide walks through how your profit is taxed, the specific expenses that matter for frame erection, how CIS deductions turn into a refund, your National Insurance, when VAT and the reverse charge bite, and the MTD timetable that is coming for everyone in construction.
As a sole trader you pay Income Tax on your profit, which is everything you invoice (labour and any materials) minus your allowable expenses. For 2025/26 the first GBP 12,570 is covered by the personal allowance, then you pay 20% to GBP 50,270, 40% to GBP 125,140 and 45% above that. Between GBP 100,000 and GBP 125,140 the personal allowance tapers away, creating an effective 60% band, though few erectors reach it. Class 4 National Insurance is 6% on profit between GBP 12,570 and GBP 50,270 and 2% above, with Class 2 NIC settled through Self Assessment.
Scottish erectors pay Scottish Income Tax through six bands (19%, 20%, 21%, 42%, 45% and a 48% top rate) and carry an S-prefixed code; Welsh erectors have a C-coded tax code at rates currently matching the rest of the UK. National Insurance stays UK-wide. CIS deductions sometimes leave a subcontractor on the wrong code or with an odd PAYE element from previous employment, so if your code looks off, run it through the tax code checker.
Frame erection is squarely within the Construction Industry Scheme. When you invoice a main contractor for your labour, they are legally required to deduct tax at source and pay it to HMRC before they pay you. As a registered subcontractor the deduction is 20%; if you have not registered for CIS it jumps to 30%, which is a pointless cash-flow penalty, so register. The deduction comes off your labour element only, not off materials you supply, and not off plant hire you pass through, provided you itemise those separately on the invoice.
Here is the crucial point: the 20% deducted takes no account of your personal allowance or any of your costs. It is a blunt withholding on your turnover. By the time you do your return, you have applied your GBP 12,570 tax-free allowance and deducted thousands in tools, van and plant costs, so your real liability is almost always lower than the sum withheld. That gap comes back as a refund. Our deeper guide for CIS subcontractors explains the mechanics, and you can model your own numbers with the CIS tax calculator.
An expense is allowable when it is incurred wholly and exclusively for the business. For this trade the list is tool-, plant- and travel-heavy, and these are exactly the costs the flat CIS deduction ignores, which is why claiming them properly is what produces your refund.
| Expense | What qualifies | Notes |
|---|---|---|
| Tools and power tools | Nail guns, framing nailers, compressors, circular and reciprocating saws, drills, impact drivers, hand tools | Larger items via the Annual Investment Allowance |
| Access and safety equipment | Harnesses, lanyards, fall-arrest gear, tool belts, edge-protection kit | Safety-critical and fully allowable |
| Plant and access hire | Telehandler, crane and mobile crane hire, scaffold and tower hire, generators | Deduct hire as a running cost; pass-through on invoices |
| Van and vehicle | Running costs (fuel, insurance, MOT, repairs) or HMRC mileage at 45p/25p | Keep a mileage log; choose one method per vehicle |
| PPE and workwear | Steel-toe boots, gloves, hi-vis, hard hats, knee pads, wet-weather gear | Protective gear allowable; everyday clothing is not |
| Site travel and accommodation | Travel to temporary sites, parking, overnight digs on distant contracts | Ordinary commuting to one regular base is not allowable |
| Insurance and certification | Public liability insurance, tool insurance, CSCS card, CITB and trade certifications | Renewals fully deductible |
| Materials and consumables | Fixings, nails, screws, straps, sealant, blades and bits | Where you supply them rather than the contractor |
| Phone, admin and accountancy | Business share of phone, bookkeeping, Self Assessment fees | Apportion any private use |
Tools are usually the single biggest deduction for an erector. A framing nailer, compressor and a decent saw kit can run to several thousand pounds. Larger items are normally claimed in full in the year you buy them through the Annual Investment Allowance, rather than spread over years, which front-loads the deduction nicely against a busy year's profit. Consumables like nails, blades and fixings are straightforward running costs. Crane and telehandler hire is a running cost too; where you arrange it but the contractor reimburses you, make sure it appears as a separate line on your invoice so it is not swept into your CIS-deductible labour.
You either claim actual van running costs (fuel, insurance, tax, servicing, repairs) with a business-use proportion, or use HMRC's simplified mileage rate of 45p per mile for the first 10,000 business miles and 25p thereafter. Pick one method per vehicle and stick with it. Crucially, travel to a series of different temporary sites is allowable, but travelling to a single site you attend for the duration of a long contract can be treated as ordinary commuting, which is not. Keep a mileage log either way. To see how your profit and refund move once these costs go in, run the figures through the sole trader tax calculator.
Everyday clothing is never allowable even though the work ruins it; only genuine PPE and protective workwear count. The private share of your van, phone and tools must be excluded. Fines, parking penalties and the cost of meals on a normal working day are not deductible. And ordinary commuting between home and a regular site does not qualify.
Construction record-keeping has one extra layer over a normal trade: the CIS paper trail. Keep every contractor's monthly deduction statement, because the tax shown on them is what you reclaim. Alongside that, keep your sales invoices (split labour, materials and plant clearly), all purchase receipts for tools and consumables, plant-hire invoices, your mileage log or fuel receipts, and your insurance and certification renewals. Photographing receipts on the day and logging payments as they clear beats reconstructing a year of muddy paperwork each January. Under MTD this becomes a requirement rather than just good practice.
For an erector, the refund is built from paperwork, not luck. The 20% is already gone; your deduction statements and your tool, van and plant receipts are what win it back at Self Assessment.
Take a registered subcontractor erector who invoices GBP 52,000 of labour over the year, with 20% deducted at source under CIS.
CIS already deducted: GBP 52,000 at 20% = GBP 10,400 withheld
Allowable expenses:
Taxable profit: GBP 52,000 minus GBP 11,300 = GBP 40,700
Income Tax: GBP 40,700 minus GBP 12,570 = GBP 28,130 at 20% = GBP 5,626
Class 4 NIC: GBP 28,130 at 6% = GBP 1,688
Tax and NIC due: GBP 5,626 + GBP 1,688 = GBP 7,314
Less CIS already deducted: GBP 10,400
Refund due: GBP 10,400 minus GBP 7,314 = GBP 3,086 back. That refund exists only because the expenses and personal allowance were claimed in full. Skip the tool and van costs and the same erector hands HMRC money they did not owe. Model your own figures with the CIS tax calculator.
You must register for VAT once taxable turnover passes GBP 90,000 in any rolling 12-month period, and a busy erector supplying labour and materials can reach that. The wrinkle for construction is the domestic reverse charge: when you supply construction services to another VAT-registered contractor who is not the end user, you do not add VAT to your invoice. You note that the reverse charge applies and the contractor accounts for the VAT instead. You still reclaim VAT on your tools, plant hire and van costs as normal. Work directly for a domestic homeowner is charged with VAT the usual way. The reverse charge is designed to stop missing-trader fraud in the sector, and getting your invoice wording right matters once you cross the threshold.
Making Tax Digital for Income Tax replaces the annual return with quarterly digital updates plus a year-end finalisation. The thresholds are on gross income, before any CIS deduction:
The trap for subcontractors is measuring against the net amount that hits your bank. The test is your gross turnover, the full invoice value before the 20% comes off, so plenty of erectors will be in scope from April 2026 even though their banked figure looks smaller. The upside is that keeping digital records continuously makes the CIS reconciliation and the year-end refund far less painful than a shoebox in January. Our guide to MTD for sole traders shows what the quarterly rhythm looks like in practice.
Staying unregistered for CIS. That means 30% withheld instead of 20%, a pure cash-flow loss until you reclaim it.
Throwing away deduction statements. They are your proof of tax paid. No statements, no clean refund claim.
Not claiming tools and plant in full. Big-ticket kit usually qualifies for the Annual Investment Allowance in the year of purchase; many erectors under-claim and overpay.
Confusing site travel with commuting. Travel between temporary sites is allowable; a long stint at one fixed site can be treated as commuting and is not.
Measuring MTD against the net figure. The thresholds use gross turnover before CIS, so check your full invoiced total, not what landed in the account.
Tax guide for Vinted sellers in the UK: trading vs selling personal items, the GBP 1,000 trading allowance, allowable expenses, the platform data HMRC now receives, VAT and MTD.
UK Airbnb tax guide: the GBP 7,500 Rent a Room scheme, the GBP 1,000 property allowance, the abolition of furnished holiday lettings, allowable expenses, VAT and MTD for landlords.
The complete UK tax guide for Uber drivers: gross fares, mileage claims, Uber service fees, VAT, and what MTD for Income Tax means for you.
UK eBay seller tax guide: selling personal items vs trading, the GBP 1,000 trading allowance, eBay fees, the platform reporting rules, VAT and MTD.
Tax guide for self-employed hairdressers: chair rent, allowable expenses, mileage, VAT and MTD for Income Tax explained in plain English.
Everything self-employed taxi and private-hire drivers need to know about tax, mileage vs actual costs, VAT, and Making Tax Digital in 2025/26.
TapTax connects to your bank, categorises expenses automatically, and submits quarterly updates to HMRC. Free plan, no card required.
