Here is an uncomfortable exercise: think back over the last month and count the business trips you made in the van. Supplier runs, quote visits, trips between jobs, the drive out to that snagging call that took ten minutes to fix. Now open your mileage log and count how many of those trips are actually in it. If the two numbers match, you are in a small minority of UK tradespeople. For everyone else, the gap between miles driven and miles claimed is money handed back to HMRC for no reason.
What the mileage allowance is actually worth
Under HMRC's approved mileage allowance payments (AMAP) scheme, sole traders using their own car or van can claim 45p per mile for the first 10,000 business miles in a tax year, and 25p per mile after that. The rate is designed to cover fuel, insurance, servicing, and wear and tear in one simple figure.
Run the numbers on a typical trade business. If you drive 8,000 business miles in a year — entirely plausible for anyone doing quotes across a couple of towns plus daily merchant runs — that is £3,600 off your taxable profit. Miss a fifth of those trips because they were never logged, and you have quietly overpaid tax on £720 of expenses you were fully entitled to. Every year. As always with tax, check the details against your own situation with an accountant, but the headline rates above are general UK facts.
Why tradespeople under-claim
Nobody under-claims on purpose. It happens for three predictable reasons:
- Forgotten trips. The big journeys get remembered. The four-mile hop to the merchant for a fitting you forgot, made three times a week, does not — and those short trips add up to serious mileage over a year.
- The reconstructed log. Come January, you sit down with a calendar and a vague memory and try to rebuild a year of driving. Reconstructed logs are always conservative, because you only write down what you can remember, and you can only defend what you wrote down.
- No record at all. Some tradespeople claim a round number that feels safe, which is usually well below reality — and a round-number guess is also exactly the kind of figure that invites questions.
What HMRC actually expects from a mileage record
HMRC does not mandate a specific format, but if your mileage claim is ever queried, you need to be able to show records that support it. In practice a defensible log captures, for each trip: the date, the start and end points, the business purpose, and the miles covered. A contemporaneous record — one made at or near the time of the trip — carries far more weight than a year-end reconstruction, for the obvious reason that it is much harder to get wrong.
You also need to keep business and private mileage separate. Commuting from home to a regular, permanent base does not count as business travel; trips from job to job, to suppliers, and to quote visits generally do. The boundaries can get genuinely fiddly — especially around what counts as a temporary workplace — so this is another area where a conversation with an accountant pays for itself.
The fix is not discipline, it is friction
The standard advice is "keep a notebook in the van" or "fill in the spreadsheet every evening". Both fail for the same reason: they rely on building a new habit around a chore. The realistic fix is to make logging a trip take less effort than deciding to skip it.
That is the thinking behind GraftG, a tool from Green & Home Ltd that is launching soon. GraftG lets you log a trip by sending a WhatsApp message the moment you park — no app to download, no dashboard, just a text to one number and a structured reply confirming the trip is captured. Because it lives in WhatsApp, it fits inside a habit you already have fifty times a day, which is the whole argument we make in our post on WhatsApp as a back office. Mileage is one of four admin jobs it handles, alongside quotes, receipts and invoices.
Building the habit before launch
Even before GraftG goes live, you can start closing the gap today:
- Log at the point of parking. Whatever your method, the trigger should be switching the engine off, not "later".
- Capture the four essentials. Date, from/to, purpose, miles. Anything less will not stand up; anything more is optional.
- Do a one-week audit. Log every single business trip for one week, multiply by your working weeks, and compare against what you claimed last year. The gap is usually eye-opening.
- Ask your accountant about edge cases. Temporary workplaces, mixed-purpose trips and home-as-base arrangements all have specific rules worth getting right.
Mileage is the rare expense where the record is the money. There is no receipt to lose — either the trip was logged or the claim does not exist. Which makes it the single highest-return piece of admin a tradesperson can fix.
GraftG is coming soon: log every trip by texting one WhatsApp number the moment you park. Register your interest at graftg.co.uk or learn more on our GraftG page.