Self-employed carpenters working under CIS supply both skilled labour and significant quantities of materials on most jobs: timber, sheet goods such as OSB and MDF, ironmongery, fixings and sealants. The CIS deduction applies only to the labour element of your invoice, not to the materials you supply, so every job where your contractor deducts from the full invoice total is a job where you are overpaying. Recovering that overpayment, combined with mileage, tools and workshop costs, typically produces a meaningful refund at year end.
CIS deductions apply only to the labour element of a carpentry invoice. Timber, sheet materials (OSB, MDF, plywood), ironmongery and fixings you supply are excluded from the deduction base. In practice, many main contractors apply the 20% rate to the full invoice rather than separating materials from labour. If your deduction slips do not reflect a correct split, you are overpaying on every job and that overpayment is recoverable through Self Assessment.
Carpenters often carry a substantial tool inventory: routers, jigsaws, circular saws, chisels, planes, clamps and site boxes. These are plant and machinery eligible for capital allowances. The Annual Investment Allowance provides a 100% first-year deduction on qualifying tool and equipment expenditure up to £1 million per year. Many carpenters claim only a fraction of what they are entitled to, treating tools as minor costs rather than a significant capital allowance claim.
Carpenters typically run a loaded van between jobs, carrying timber, sheet materials and tools. You can claim the actual running costs of the van (fuel, insurance, road tax, servicing, finance interest) or the AMAP rate of 55p per mile for cars and vans from 6 April 2026. For high-mileage tradespeople the actual-cost route often produces the larger deduction. We calculate both and use whichever is correct for your situation.
A self-employed carpenter who is not registered for CIS will have 30% deducted from their labour income rather than 20%. On £40,000 of annual labour income, that gap costs £4,000 a year. CIS registration is free and cuts the deduction rate immediately. We check your registration status and fix any verification issues with HMRC that might cause a contractor to apply the higher rate.
We review your payment and deduction statements, verify the labour/materials split on each job, account for all allowable expenses including tools, van costs and mileage at 55p per mile, and submit your Self Assessment return to recover the full refund. Most carpenters receive their refund within 8 to 12 weeks of a correctly filed return.
We identify every qualifying tool and item of equipment and claim the correct capital allowance. For a carpenter who has invested in a new tool set, workshop equipment or site machinery in the year, this can significantly reduce the Self Assessment tax bill.
If your net annual CIS turnover (labour income, excluding materials and VAT) exceeds £30,000, you may qualify for GPS and receive payments with no deduction at all. We handle the application, the three qualifying tests and the compliance record that keeps GPS in place.
“I had been splitting out materials on my invoices but my contractor was still deducting from the full amount. Once the statements were reviewed and corrected at year end, the refund was considerably more than I had budgeted for.”
Composite snapshot based on client patterns. Name and figures anonymised. The tax mechanics are real.
Book a free call. We will talk through your CIS position, your deduction history and whether there is anything worth changing. No hard sell, no obligation.
Other trades we work with