What expenses can a CIS subcontractor claim?

Self-employed CIS subcontractors can claim costs used only for their business: tools, materials, van costs or 55p a mile in 2026-27, protective clothing, the business share of their phone, insurance and training. Personal costs are not allowed.

Every pound of allowable expense lowers your profit, and your tax and National Insurance are worked out on profit. With 20% taken from your pay under the Construction Industry Scheme (CIS), claiming your costs properly can mean a bigger refund or a smaller bill.

The main expenses for trades

All of this comes from GOV.UK's guidance for the self-employed, checked on 16 October 2026.

Vans and mileage

You choose one of two methods for each vehicle. You can claim the business share of the actual running costs, or a flat rate per business mile. For 2026-27, GOV.UK's simplified rate for cars and goods vehicles, including vans, is 55p a mile for the first 10,000 business miles and 25p after that. Before 6 April 2026 the first rate was 45p.

You cannot use the flat rate on a vehicle you have already claimed capital allowances for or included as an expense. Once you use the flat rate for a vehicle, you must keep using it for as long as that vehicle is used in your business. Parking and train fares can be claimed on top.

Buying a van. Under the cash basis, now the default for sole traders, GOV.UK says a business vehicle other than a car is claimed as an expense. A car goes through capital allowances instead. If you claim the van's cost, you cannot then use the mileage rate for it.

Travel from home to site

GOV.UK says travel between home and work cannot be claimed. For most subcontractors, though, there is no fixed workplace. HMRC's Business Income Manual says an itinerant trader, such as a jobbing builder, who works from home at a series of temporary sites can claim travel between home and those sites. If you go to the same site every day for a long contract, that travel looks more like commuting, so keep a log of where you worked.

What this means for you

A simple example: a self-employed joiner in 2026-27 drives 8,000 business miles in their van, claims £4,400 at 55p a mile, and has £1,600 of tools, £300 of safety gear and £420 of business phone costs. That is £6,720 of expenses. If the joiner lives outside Scotland and their profit is in the basic rate band, that is £1,344 less Income Tax at 20% and £403.20 less Class 4 National Insurance at 6%.

If your costs are very low, you can instead take the £1,000 trading allowance, but then you cannot claim any expenses. Most trades with a van and tools are better off claiming actual costs.

Steps to claim your expenses

1. Keep every receipt and invoice, on paper or as a photo. You do not send them with your return, but HMRC can ask to see them.
2. Keep a mileage log: date, site, purpose and miles.
3. Decide for each vehicle whether you use the mileage rate or actual costs, and stick with it.
4. Work out the business share of anything you also use personally, such as your phone.
5. Add the totals to the expenses boxes on your tax return, and put your CIS deductions in their own box, not as a cost.
6. Under Making Tax Digital, record costs digitally as you go so each quarterly update includes them.

Use the free MTD check to see when Making Tax Digital starts for you, and see the trades section for more on CIS.