MilometryWhat makes HMRC look twice at a mileage claim
Round numbers, impossible days, claims that never change, and the other patterns that invite a question you would rather not answer.
Information générale, pas un conseil. Rédigé à titre d’information générale et exact à notre connaissance au 27 septembre 2026. Les règles fiscales changent et leur application dépend de votre situation. Ceci n’est pas un conseil fiscal, juridique ou financier : vérifiez auprès d’un expert-comptable, d’un conseiller fiscal ou de l’administration fiscale avant de vous y fier.
HMRC does not publish how it picks claims to query. In our view, the claims that draw questions tend to share a handful of characteristics, and they are rarely about the amount alone.
Round numbers everywhere
Real driving does not produce round numbers. A month of genuine journeys totals 847 miles, not 850. A claim made of tidy fifties and hundreds looks estimated because it usually is.
This is a common tell, and it is entirely avoidable: record the distance you actually drove.
The same figure every month
A claim of exactly 500 miles in twelve consecutive months describes a standing order, not a working year. Real mileage moves with holidays, weather, illness, quiet Augusts and busy Novembers.
If your driving genuinely is that regular, the record will show it, but it will show it as 512, 486, 503, not 500 twelve times.
Days that could not have happened
Claims that require being in two places at once, or covering 400 miles in a working day that also contained six hours of meetings, do not survive contact with a calendar. Reconstructing a year from memory produces these without anyone intending to mislead.
No evidence of the journey's purpose
The distance is only half of it. HMRC's expectation is that you can say why a journey was business, which client, which site, which job. "Business mileage: 340" is a number, not a record.
Commuting mixed in
Home to a permanent workplace is ordinary commuting and is not claimable, and a claim that quietly includes it is a common and costly mistake: a substantive error rather than a presentational one. If a pattern of identical journeys on identical weekdays runs through the log, it invites exactly the question you do not want.
Patterns that tend to invite questions
This is our own reading of what stands out, not a list HMRC publishes.
| Pattern | How obvious | Why it draws attention |
|---|---|---|
| Round numbers throughout | Very | Real driving is not round |
| Identical total every month | Very | Describes a standing order, not a year |
| Impossible days | Very | Fails against a calendar |
| Commuting included | High | A repeating weekday pattern is visible |
| No purpose recorded | High | A distance is not a record |
| Claim jumps sharply year on year | Medium | Invites "what changed?" |
| Mileage inconsistent with fuel receipts | Medium | Two of your own records disagree |
| Claim inconsistent with the odometer | Medium | Easy to check at MOT |
What your claim can be checked against
Most of these are your own documents, which is why a consistent record is so much stronger than a plausible one:
| Cross-check | What it reveals |
|---|---|
| Your calendar | Whether the meetings existed |
| Your invoices | Whether the client was visited that week |
| Fuel receipts | Whether enough fuel was bought to cover the miles |
| MOT odometer history | Whether the car covered the distance at all |
| Employer's reimbursement records | Whether the figures agree |
What a good record looks like
For each journey: the date, where you went from and to, why it was business, and how far. Kept as you go, not assembled afterwards. Employees who file a tax return should keep records for at least 22 months after the end of the tax year. The self-employed should keep them for at least 5 years after the 31 January filing deadline. If you might backdate a claim, keep the records for every year you claim.
The reason contemporaneous records matter is not bureaucratic. It is that they are checkable, against your calendar, your invoices, your fuel receipts and your odometer, and a claim that agrees with four other sources is not a claim anyone spends long on.
The quiet advantage of recording automatically
A log that writes itself as you drive is contemporaneous by definition. It produces the awkward, specific numbers real driving makes, it carries the route rather than just the total, and it cannot accidentally include the school run because nobody was reconstructing anything in April.
Milometry records each journey as it happens, keeps commuting out of the claim once home and workplace are tagged, and exports the year as a CSV or PDF that shows the individual journeys rather than a monthly figure.
Sources
- How long to keep your records: employees and others filing a tax return (HMRC)
- How long to keep your records if you're self-employed (HMRC)
- 490: Tax and National Insurance contributions for employee travel (HMRC)
- Ordinary commuting and private travel: 490 chapter 3 (HMRC)
- Claim tax relief for your job expenses: vehicles you use for work (HMRC)
- Travel, mileage and fuel rates and allowances (HMRC)
General information for UK drivers, not tax advice.
