Half the questions accountants get start with the same three words: “Is this allowable?” Here’s the one rule behind all the answers, and plain verdicts on the expenses that come up most.
The rule: a cost is allowable when it’s incurred wholly and exclusively for the business. Where something is genuinely part-business, part-personal — like a phone — you claim an honest business proportion. Everything below is that rule, applied.
Your mobile phone
Yes, proportionally. If your mobile is basically a second office, you can claim the business share of the bill. That “I use it for work” feeling needs to become an honest percentage — keep it reasonable and it’s generally allowable.
The van (or car)
Yes — pick a method. Either claim a fixed rate per business mile (HMRC’s simplified mileage rate covers fuel, insurance and wear), or claim the business proportion of actual running costs. Mileage is simpler; actual costs sometimes win for heavier use. Either way: the school run is not a business journey, and a mileage log is your best friend.
Work clothing
Mostly no — with real exceptions. Everyday clothing isn’t allowable even if you only wear it for work. The exceptions: genuine protective gear (steel toe caps, hi-vis) and branded uniform with your logo. A suit for client meetings counts as everyday clothing, so that one stays personal.
Lunch on the job
Usually no, sometimes yes. Day-to-day lunch is a personal cost — everyone eats. Reasonable food and drink can become allowable when you’re travelling for work outside your normal pattern — an overnight stay, or a genuinely irregular journey. The everyday sandwich near the job: no.
Training and courses
Yes, to stay sharp — not to change lanes. Training that maintains or updates skills you already use in the business is generally allowable. A course to enter a brand-new line of work is different — that’s usually “new skill” territory and generally not allowable for sole traders.
Working from home
Yes, proportionally. Do your books at the kitchen table? You can claim either HMRC’s flat rate for the hours you work from home, or a calculated share of household costs. Small numbers, but they add up over a year.
Your accountant
Yes. Accountancy fees for the business are allowable — which takes some of the sting out of the fee, and none of the value out of the advice.
When in doubt, the sequence is: honest proportion, kept record, asked someone. Asking first is always cheaper than claiming optimistically and finding out later. If a specific expense is on your mind, send us the question — plain verdicts are what we do.
This guide is general information, not advice for your specific circumstances. Tax rules change, and how they apply depends on your situation — if you'd like to talk yours through, we're happy to help.
Quick answers
What does “allowable expense” actually mean?
An allowable expense is a business cost HMRC lets you deduct from your income before your tax is worked out — so you only pay tax on your actual profit. The core test is that the cost was incurred wholly and exclusively for the business.
Can I claim expenses without receipts?
You need records to back up what you claim — receipts, invoices or bank statements. A photo on your phone is fine. No evidence at all means a claim that won’t survive scrutiny, so build the habit of capturing things as they happen.
What happens if I claim something I shouldn’t have?
Honest mistakes are usually corrected with an amended return and any extra tax paid — it happens. But a pattern of over-claiming can bring penalties and unwelcome attention, which is why “when in doubt, ask first” is cheaper than “claim it and hope”.