No has nothing to do with tax. Usually contractors have very fixed scope, they focus on doing what is in the contract. Sometimes things that come up ad-hoc like marketing requesting installation of Google tag Manager, is outside the scope of the contract. It would require a lot of giving them context, amending contract etc... It's not necessarily convenient to have to ask them to come in every time there is a problem.

Usually I try to reason with management first. If it can be resolved internally we would not include outside consultants, however if it gets serious beyond something we can handle internally we would ask outside consultant to come in.