You have to be paid for all work you did, not matter what structure you performed the work under. (You don't have to be double paid, so if you billed for the same work or time on a corp-to-corp basis and also as a W2 employee, they only need to pay you once for it.) It does not matter if their client is unhappy, or did not pay them, or if they then considered this grounds to terminate you: if you did the work, you must be paid. And to stress a critical point: their inability to be paid by the client has NOTHING to do with their obligations to you or your right to be paid. Even if they are not paid for the work you did, they have to pay you; they can sue their client for any money owed to them if the choose, but that is their concern, not yours. If they will not pay you for any work you did, you could sue them (e.g. in small claims court) for the money.