You would have often seen a contract containing a provision saying that the consultant will do everything required, but if the consultant uses subcontractors, then the fee will increase to accommodate the extra expense. Please don't use such clauses. This clause simply states you don't know your client's job. This ultimately spoils the client-relationship hampering your future billings. In fact, you should just do the opposite. Tell the client that the fee is for the entire project and you’ll decide whether you need subcontractors' help and you won't charge extra for that. Further, if the client wants you to do all the work yourself in order to keep a single “filter” in place or guarantee a single qualitative source, there is a 10 percent premium on the fee. In other words, it costs more if you're the only one to work on the project, not less. You're the talent; the subcontractors are not.