Written by the TaxTune Editorial Team·Reviewed by our qualified accountants·Updated June 2026

Common allowable expenses

The rule that decides whether a cost counts is the wholly and exclusively test. A cost is allowable if you incur it only for your work. Where something is used partly for work and partly privately, you claim the business proportion. For a self employed construction worker, the most common allowable costs include the following.

  • Tools and equipment. Drills, saws, trowels, levels, ladders and other kit you buy to do the job. Smaller tools are a straightforward expense, and larger equipment can be claimed in full using the Annual Investment Allowance, which gives 100% relief on qualifying purchases up to £1,000,000 a year.
  • Protective clothing and PPE. Hard hats, safety boots, hi vis vests, gloves, goggles, ear defenders and overalls. Protective gear is allowable even though everyday clothing is not.
  • Materials you pay for. Bricks, timber, cement, fixings and any consumables you buy and use on a job rather than the client supplying them.
  • Travel to temporary sites and mileage. Travel from your base to a temporary workplace is allowable. If you use your own vehicle you can claim mileage at 45p for the first 10,000 business miles in the year and 25p for each mile after that.
  • Van running costs. If you prefer to claim actual costs rather than mileage, you can claim the business share of fuel, insurance, road tax, repairs, servicing and breakdown cover for a work van.
  • Insurance. Public liability cover and tool insurance are allowable business costs.
  • Phone. The business proportion of your mobile phone and any work calls.
  • Training and tickets. Courses and cards that keep your existing skills current, such as a CSCS card, count as allowable. Renewing a ticket you already hold is the clearest example.

For more on how these costs sit within a return, see our guide to Self Assessment allowable expenses.

Expenses people often miss

Construction workers frequently leave money on the table because some costs are easy to overlook. Common ones include the following.

  • Small consumables and sundries. Blades, screws, sandpaper, tape and other low cost items add up across a year and are all allowable.
  • Replacing worn tools. When a tool wears out and you buy a like for like replacement, that cost is allowable.
  • Cleaning of protective clothing. The cost of laundering or replacing overalls and work specific clothing.
  • Use of home for admin. If you handle quotes, invoices and paperwork from home, a reasonable share of household running costs can be claimed.
  • Accountancy fees. The cost of preparing your accounts and Self Assessment return is itself an allowable expense.
  • Bank charges and interest. Charges on a business account and interest on borrowing used for the business.
  • Parking and tolls. Site parking and tolls incurred while travelling for work, on top of your mileage.

Keeping a simple record as you go means none of these slip through. Our bookkeeping service can take this off your hands so nothing is missed.

Risky or commonly challenged expenses

Some costs are commonly challenged by HMRC, so it pays to understand the limits before you claim.

  • Everyday clothing. Jeans, jumpers and ordinary footwear are not allowable even if you only wear them on site. Only genuine protective clothing or a branded uniform qualifies.
  • Ordinary commuting. Travel to a permanent workplace is not allowable. The rules turn on whether a site is temporary, so be ready to show why a journey qualifies.
  • Client entertaining. Buying drinks or a meal to win or keep work is never allowable, no matter how normal it feels in the trade.
  • Food and drink. The cost of everyday meals while working is generally not allowable, with only limited relief for genuine travel away from your usual pattern of work.
  • Mixed use without a split. Claiming a phone, vehicle or tool in full when it is also used privately invites a challenge. Always apply a fair business proportion.
  • New skills rather than maintaining skills. Training that gives you an entirely new trade is treated differently from training that keeps your current skills up to date.

The safest approach is to claim what the job genuinely needs and to keep the evidence that supports each cost.

Records to keep

Good records protect your claim and make your return quick to complete. As a self employed worker you should keep your records for at least 5 years after the 31 January Self Assessment deadline they relate to.

  • Sales records. Invoices you raise and the payments you receive, including any CIS deduction statements from contractors.
  • Receipts and invoices for costs. Tools, materials, PPE, insurance and van expenses. Photograph paper receipts before they fade.
  • A mileage log. The date, journey, reason and miles for each work trip if you claim mileage.
  • Bank statements. Ideally from a separate account used only for the business.
  • CIS statements. Each contractor must give you a statement showing the tax deducted. These are the proof behind your refund.

If you want figures to estimate your position before filing, our tax calculators can give you a quick sense of where you stand.

A worked example

Worked example

A self employed bricklayer within CIS

Daniel is a self employed bricklayer working for several contractors under CIS. In 2026/27 he is paid £42,000 for his labour. Because contractors deduct 20% from labour for registered subcontractors, £8,400 in CIS tax has already been taken from his pay before he received it, and that deduction applies only to labour and not to any materials. During the year Daniel spends £3,200 on tools and equipment, £600 on protective clothing, and drives 9,000 business miles to temporary sites, giving mileage relief of £4,050 at 45p a mile. His allowable expenses come to roughly £7,850, so his taxable profit is about £34,150 rather than the full £42,000. Once his personal allowance and the lower tax bands are applied, the tax actually due on that profit is far less than the £8,400 already deducted. The overpaid amount is reclaimed through Self Assessment, and Daniel receives a refund.

The exact figures depend on his full circumstances, but the pattern is typical: expenses plus CIS deductions usually mean a refund is due.

Common mistakes

A few avoidable errors cost construction workers money or invite questions from HMRC.

  • Not claiming because tax is already deducted. CIS deductions are an estimate taken at source. Without a return that claims your expenses, you cannot recover the overpayment.
  • Losing CIS statements. Missing statements make it hard to prove how much was deducted, which can delay or reduce a refund.
  • Forgetting small costs. Consumables, parking and replacement tools are easy to skip but add up over a year.
  • Claiming everyday clothing. Only protective clothing and uniforms qualify.
  • Mixing personal and business spending. A separate account makes your records far cleaner and your claim easier to support.
  • Leaving filing to the last minute. Rushing a return often means missed expenses and a smaller refund.

If you are unsure how the scheme affects you, see how CIS refunds work in practice.

What you should do

Start by gathering every cost from the year and every CIS statement from your contractors. Add up your allowable expenses, check your mileage records, and compare the tax due on your profit with the amount already deducted. In most cases you will find a refund is waiting.

If you would rather have it handled accurately and on time, we can prepare your return, claim every allowable expense and recover what you are owed. See our work with construction clients on our accountants for construction page, or get a fixed fee quote to get started.

In short

A practical guide to the expenses self employed construction workers can claim and how CIS deductions usually lead to a refund.

Frequently asked questions

Will I get a tax refund if I work under CIS?
Very often, yes. Contractors deduct 20% from your labour at source, which is an estimate rather than your actual tax bill. Once your allowable expenses and personal allowance are taken into account, the tax genuinely due on your profit is usually less than the amount already deducted. The overpaid amount is reclaimed through Self Assessment, and many construction workers receive a refund each year.
Can I claim my tools and a new drill?
Yes. Tools and equipment you buy for your work are allowable. Smaller tools are a straightforward expense, and larger purchases can be claimed in full through the Annual Investment Allowance, which gives 100% relief on qualifying items up to £1,000,000 a year. Replacing a worn tool with a like for like one is also allowable.
Can I claim travel to site?
You can claim travel from your base to a temporary workplace. If you use your own vehicle you can claim mileage at 45p for the first 10,000 business miles in the year and 25p a mile after that, or you can claim the business share of actual van running costs instead. Travel to a permanent workplace counts as ordinary commuting and is not allowable.
Is a CSCS card an allowable expense?
Yes. The cost of cards and tickets that keep your existing skills current, such as a CSCS card, is allowable. Renewing a ticket you already hold is the clearest example. Training that maintains your current skills is allowable, while training that gives you an entirely new trade is treated differently.
How long should I keep my records?
If you are self employed you should keep your records for at least 5 years after the 31 January Self Assessment deadline they relate to. That includes invoices you raise, receipts for your costs, a mileage log and the CIS statements from each contractor, which are the proof behind any refund.