If you use subcontractors you will always want to make sure they have their own work comp policies. If they do not, you will be hit for their costs come audit time. Not only do you want to collect certificates from them, you want to have them sign a contract which makes certain their insurance pays first. In most policies, waiver of subrogation, primary non-contributory and indemnity clause are only enforced if there is a contract in place between you and your subcontractor. We have a method of protecting our clients in this area. Why should you carry the risk when it is easily transferable?