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7 Allowable Expenses Subcontractors Often Forget to Claim

Illustration of a receipt, calculator and wrench, representing claimable business expenses for subcontractors

If you're self-employed in construction, you're taxed on your profit, not your turnover, which means every legitimate business cost you don't claim is tax you're paying unnecessarily. These are the ones we see missed most often.

1. Tools and small equipment

Hand tools, power tool batteries, blades, drill bits, and other consumables used for work are generally allowable. Larger, longer-lasting equipment (like a new set of power tools) may need to be treated slightly differently as a capital cost, but it's still generally relievable, just ask us which category applies.

2. Protective clothing and workwear

Hi-vis, steel-toe boots, hard hats, gloves, and branded workwear bought specifically for the job are allowable. Everyday clothing you'd wear regardless of work isn't, so the distinction is whether it's genuinely work-specific.

3. Vehicle costs and mileage

Getting yourself and your tools to site is a real cost of doing business. Whether you claim actual running costs or a simplified mileage rate depends on your circumstances, but this is consistently one of the largest allowable expenses subcontractors under-claim, mainly because they don't keep a mileage log.

4. Materials you've paid for yourself

If you've bought materials for a job out of your own pocket and haven't already been separately reimbursed for them, they're a cost of doing the work and should be claimed.

5. Insurance

Public liability insurance, tool insurance, and other cover you hold specifically for your trade are allowable business expenses.

6. Phone and admin costs

If you use your phone for calling clients and suppliers, arranging jobs, or admin, the business proportion of that cost is claimable. The same applies to accountancy fees, and to a proportionate share of home office costs if you handle paperwork and quotes from home.

7. Training and certifications relevant to your trade

CSCS card renewals, first aid certificates, and training that maintains or updates skills you already use in your trade are generally allowable. (Training for a completely new trade or qualification is treated differently, so it's worth checking with us if you're branching out.)

The real cost of under-claiming None of these individually look like much. Added up over a year, missed expenses across these categories routinely run into hundreds or thousands of pounds of profit that gets taxed unnecessarily, simply because the receipts weren't kept or the costs weren't mentioned.

The habit that actually matters

None of this requires perfect bookkeeping. It requires keeping receipts (a phone photo is fine) and a simple mileage log, and passing them to your accountant rather than assuming small costs aren't worth mentioning. They usually are.

This article is general guidance for UK construction businesses and does not constitute personal financial or tax advice. Rules, thresholds and individual circumstances vary, so always confirm your specific position with us before acting on it.
Rehan Razzaq
Written by

Rehan Razzaq, FCCA

Founder, BuildRight Accountants

ACCA Chartered Certified and a Xero Certified Advisor, helping UK construction businesses with accounts, tax and financial planning.

More about Rehan →

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Frequently Asked Questions

Do I need a receipt for every expense I claim?

Ideally yes. A phone photo is enough for HMRC's purposes, but you should be able to produce evidence for anything you claim if asked.

Can I claim expenses I paid for before I registered as self-employed?

Some pre-trading expenses can be claimed if they were incurred wholly for the business shortly before you started, but the rules are specific, so check with us before claiming them.

What's the difference between claiming mileage and claiming actual vehicle costs?

Mileage is a simplified flat rate per mile; actual costs means claiming a business proportion of running costs, fuel, insurance and depreciation. You generally choose one method per vehicle and stick with it.

Can I claim for tools I already owned before going self-employed?

Only the business-use proportion, and larger items may need to be treated as a capital cost rather than a straightforward expense.

Will claiming more expenses increase my chance of an HMRC enquiry?

Claiming expenses you're legitimately entitled to doesn't increase risk on its own. What matters is that what you claim is genuine, business-related and evidenced.