Tax rule UK
Business use: your vehicle and your home
How HMRC asks you to split a vehicle's and a home's costs between business and private use, and the years Bilbx's Tax Lab applies each split for.
The record for a vehicle
Mileage log, for its own year
Checked against HMRC's own pages on . This is the figure Bilbx uses.
The rule
You cannot claim non-business driving or travel costs, or travel between home and work.
What GOV.UK says
“non-business driving or travel costs”
“travel between home and work”
For working from home, find a reasonable method of dividing your costs, for example by the number of rooms you use for business or the amount of time you spend working from home.
What GOV.UK says
“You’ll need to find a reasonable method of dividing your costs, for example by the number of rooms you use for business or the amount of time you spend working from home.”
How Bilbx applies it
- Tax Lab, part of Bilbx Premium, applies a category's business-use share for the tax years its record covers: mileage log, for its own year; usage record, for its own year; rooms or floor area, until you change it.
- When a record no longer covers the year, Settings asks for a new one.
Worked examples
Bilbx's own tests run these exact cases against the website and the app.
| Record | Made in the tax year starting | Read in | Tax Lab |
|---|---|---|---|
| Mileage log | 2025 | 2025 | Applies the share |
| Mileage log | 2025 | 2026 | Asks for a new record |
| Rooms or floor area | 2020 | 2030 | Applies the share |
Sources
Spotted something that doesn't match HMRC's guidance?
Every sentence in the rule is checked against HMRC's own guidance, quoted beneath it and linked above. Last checked . Rules version 60f9162250af. Terms.
More for the UK: every tax rule Bilbx applies and guides on receipts and tax records.