You could in theory notify under more than one clause, but if you are using a cloud based system it normally only allows you to choose one reason. In that case I would pick the most obvious one (or sometimes the one most palatable to the Employer, as they may have a particular risk pot to use for certain reasons e.g. lack of access). In the text of the notification you can then also list the other reasons it could have been notified under. This should make it clear it definitely is a CE one way or another.
It just stops them rejecting for one reason, and you then notifying again for another reason. If it is a CE, it doesn't matter what number it is notified under as the cost.time effect will be assessed the same way.
It just stops them rejecting for one reason, and you then notifying again for another reason. If it is a CE, it doesn't matter what number it is notified under as the cost.time effect will be assessed the same way.