HMRC will be running a digital campaign aimed at encouraging accurate private use adjustments of business expenses that are reported via Self Assessment returns.
MRC have announced that they’ll be stepping up checks on private use adjustments made to business expenses claimed through Self Assessment.
The rules in simple terms
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To be allowable for tax, expenses must be “wholly and exclusively” for business purposes.
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If an expense has a mixed business and personal use, you can only claim the business proportion.
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You must make a reasonable apportionment based on the actual use in that tax year.
What prompted this?
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In 2024, HMRC ran a digital trial with 600,000 taxpayers, encouraging them to adjust for private use.
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The results showed widespread errors – many claims still included personal use elements.
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As a result, HMRC have confirmed they will now be opening more enquiries into private use claims.
Examples of where this applies
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Motor expenses – petrol, insurance, repairs where the vehicle is also used personally.
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Telephone & broadband – only the business portion is allowable.
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Home office costs – claims must be based on the actual business use of space and time.
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Subscriptions / memberships – personal elements should be excluded.
What this means for you
HMRC are clearly making this an area of focus. If your Self Assessment includes business expenses with a private element, it’s important you:
✅ Keep clear records (e.g. mileage logs, usage breakdowns).
✅ Make sensible and fair apportionments.
✅ Be prepared to evidence how you worked out the business vs private use split.