When does health screening become tax free?

I am not sure of the rules about health screening. Under what conditions does it become a tax free benefit? I believe, but am not sure, that the rule is as long as its a benefit available to the whole workforce it is tax-free. Can anybody help me please?

Employer funded health checks

HMRC changed their approach in 2008 and this change was included in the Finance Act 2009.  The change means that currently health checks are tax exempt and there is no requirement to offer them to all staff either.

The detail is shown on the HMRC website under one of their manual sections, as follows:

http://www.hmrc.gov.uk/manuals/eimanual/eim21765.htm