I have a client who is administering their own retiree benefits and is charging an administration fee onto the dental/health premiums thay are charging the retiree. Is this possible? and where can I find information on this.

I am wondering, why wouldn't it be possible? It is a legitimate cost of running the plan. If it were being administered by an insurance carrier, their admin costs would either be built into the premium or would be a stated % of paid claims, etc. As long as it's reasonable and in writing, I don't see a problem.