how can you tax something that people are entitled to, but don't
actually use


HMRC do it all the time. Eg the common one is employees who get
employer-provided private medical insurance but make no claims.

But there's also employees who have employer-provided accommodation
available to them but don't use it in a tax year; employees who have a
car available to them for private use by reason of their employment but
do not use it; .............

Let me know if you want more boring stuff about the taxation of benefits
in kind which I am sorry to say I have yet to forget entirely

--
Robin
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