If an employee incurs the cost of a doctor's certificate at the request of their employer is this cost incurred wholly, exclusively and necessarily for the purposes of the employment so that there is no tax on this item?
If this were a benefit provided by the employer, it would not be taxable.
http://www.hmrc.gov.uk/manuals/eimanual/EIM21765.htm
So, what conclusion can we draw?
Firstly that a general medical is not deductible from employment income. This is why the legislation permits a tax-free benefit.
However, I feel that if this is required by an employer, then it is likely to be necessarily. Without this certificate, the individual is likely to be unable to carry out his tasks.
The best way round this would be via salary sacrifice and the employer picking up the tax. Then it would clearly be a benefit.