Temporary workplace mileage and HMRC's 24-month rule

For a Tesla mileage log, the route alone is not enough. Home → Office may be private ordinary commuting, while Home → Project Site may be eligible business travel if the site is genuinely temporary. The tax result depends on why the employee attends that workplace, how long the attendance is expected to last and how much working time is spent there.

1. What is a temporary workplace?

HMRC describes a temporary workplace as a place an employee attends only to perform a task of limited duration or for another temporary purpose. A workplace can therefore be visited regularly and still be temporary if the reason for attendance is genuinely limited or temporary.

This matters because qualifying travel to a temporary workplace can be treated differently from ordinary commuting to a permanent workplace.

2. The 24-month rule

A workplace cannot remain temporary under the limited-duration rule where the employee attends it in a period of continuous work that lasts, or is expected to last, more than 24 months. In that situation HMRC treats the workplace as permanent and home-to-work travel becomes ordinary commuting.

3. The expectation can change before month 24

The rule is not simply a stopwatch that expires after two years. HMRC looks at what is expected based on the facts at the time.

For example, if an employee starts an 18-month posting, the site may initially be temporary. If after 10 months the posting is extended so that total expected attendance becomes 28 months, HMRC's example treats the workplace as permanent from the date the expectation changes. Travel relief can therefore stop before the employee has physically spent 24 months there.

The reverse can also happen: if a posting originally expected to exceed 24 months is later shortened so that it is no longer expected to exceed the limit, the workplace can become temporary from that change in expectation.

4. Why the 40% rule matters

For the 24-month rule, HMRC regards duties as performed to a significant extent at a workplace where the employee spends 40% or more of working time there. This means that calendar duration alone does not tell the full story.

A useful mileage record may therefore need more context than total miles:

• Which workplace was visited
• Why the employee attended it
• When attendance started
• The expected end date or project duration
• How regularly the employee attends
• Whether the workplace is permanent, temporary or needs review

5. Ordinary commuting stays private mileage

Travel between home and a permanent workplace is ordinary commuting and is normally private travel for HMRC purposes. That means the same physical journey can change tax treatment if the status of the workplace changes.

6. A break does not necessarily reset the clock

HMRC also warns that a period of continuous work can remain continuous even where there is a break in attendance. Moving to a nearby site may not necessarily create a new workplace either if the change has no substantial effect on the journey. For complex projects, contractors and rotating sites, the detailed facts matter.

7. How DriveQuery can make temporary-workplace mileage easier

DriveQuery can collect a factual trail of journeys through the Tesla connection and turn that into a review workflow instead of asking the employee to reconstruct every site visit months later.

1. Record the Tesla journey, date, start, destination and distance.
2. Recognise recurring destinations such as a project site or client location.
3. Suggest Business · Temporary workplace where the user has previously confirmed that context.
4. Keep new sites and changes in working pattern in a review queue.
5. Track the first attendance date and a user-confirmed expected end date.
6. Flag long-running sites for review rather than silently treating every journey as business mileage forever.

8. What should the mileage record keep?

Where an employee is claiming mileage or tax relief, the record still needs to support the underlying business journey. A practical Tesla mileage log should keep:

A business mileage tracker can preserve the journey trail while the workplace facts are still fresh. For the value of qualifying miles, use the HMRC mileage rates calculator.

Illustrative record only. The tax treatment still depends on the employee's actual facts and HMRC workplace rules.

A useful system therefore stores what happened separately from how the journey was treated. The Tesla can provide much of the journey evidence; the employee or employer confirms the temporary-workplace context and any change in the assignment.

• Date and time
• Start and destination
• Distance
• Journey purpose
• Workplace name or project
• Business / commute / private classification
• Temporary-workplace status where relevant
• Notes explaining unusual or changed circumstances

For an employee using their own Tesla, qualifying business miles can then feed into the 2026/27 HMRC mileage-allowance calculation. See the 55p and 25p business mileage guide.

Frequently asked questions

Sources: HMRC – Ordinary commuting and private travel (Chapter 3), HMRC EIM32075 – temporary workplace, HMRC EIM32080 – the 24-month rule and HMRC EIM32105 – breaks in attendance., HMRC EIM32084 – expectation changes during an assignment