HMRC Booklet 480 section 6.7 deals with assets placed at the disposal of an employee with the benefit being calculated as 20% of the market value of the asset when first provided. If there are days when the asset is not available for private use, a reduction will be made in the value of the benefit. An asset is unavailable for private use if not in condition fit for use, is undergoing repair or maintenance or cannot be lawfully used.
The section goes on to state that "An asset is also treated as unavailable for private use if on a day the employee uses the asset in the performance of the duties of their employment and doesn't use the asset otherwise".
How do you determine a day where the asset is used in the performance of the duties of employment?