This is general guidance, not personalised tax advice. HMRC's approved mileage rates and thresholds change — check gov.uk or your accountant for current figures.
Vehicle costs are one of the largest expenses a tradesman carries, and one of the least accurately tracked. Most reconstruct a rough mileage figure at year end from memory, or don't claim vehicle costs properly at all because building a log after the fact feels pointless. Neither serves you well — HMRC expects contemporaneous records, and under-claiming a legitimate cost is money left on the table.
Two ways to claim vehicle costs
- Simplified mileage rate — HMRC's approved mileage rate per business mile (historically 45p for the first 10,000 miles a year by car or van, 25p after that), covering fuel, wear and insurance in one flat rate. No need to track individual running costs, but you still need a mileage log.
- Actual costs — claiming a business-use percentage of real running costs (fuel, insurance, servicing, finance), which can work out higher for a vehicle used almost entirely for the business, but needs every receipt kept and a clear business-use split.
Whichever method, the mileage log itself is not optional — HMRC expects a record of each business journey, not an estimate produced later.
What a proper mileage log needs
- Date of the journey
- Start and end points (or postcodes)
- Purpose of the trip — which job it relates to
- Miles driven
That last point — tying mileage to a specific job — is where most mileage trackers fall short. A generic mileage app gives you a yearly total for HMRC. It doesn't tell you that Job A involved four extra trips to a merchant that ate into its margin.
Why job-level mileage matters, not just the yearly total
A job that needed six site visits and two extra merchant runs costs more in vehicle time and fuel than one finished in a single visit — but if mileage isn't tagged to the job, that cost is invisible until the whole year's fuel bill is totalled up. Tracking mileage per job shows you which jobs are quietly more expensive to run, not just what the total tax deduction comes to.
Spreadsheet vs app
| Method | What actually happens |
|---|---|
| Memory, reconstructed later | Rough estimate, rarely accurate, doesn't survive an HMRC query. |
| Paper mileage book | Accurate if kept up, usually abandoned within a month. |
| Spreadsheet | Works if you log every trip same-day — most people don't. |
| App logging mileage per job (like Site Wallet) | A trip logged in seconds, tagged to the job it was for, rolled into that job's real cost. |
How Site Wallet handles vehicle costs
Mileage and fuel receipts tag to a job exactly like any other cost, so a job's running total includes what it actually cost to get there and back — not just materials and labour. At year end, export the same records for whichever method your accountant uses to calculate your vehicle claim.
FAQ
Can I switch between the mileage rate and actual costs each year?
Generally, once you choose the mileage rate method for a vehicle, HMRC expects you to stick with it for that vehicle for as long as you use it for business. Check with your accountant before switching.
Do I need to log personal journeys too?
You don't need to claim for them, but a mileage log should clearly separate business and personal use so the business mileage total is defensible if HMRC ever asks.
What if I've been estimating my mileage for years?
Going forward, log every business trip as it happens — a defensible, contemporaneous log from today onward is far stronger than trying to fix historic estimates retroactively.