Some agencies are have a list of umbrella companies that you are ‘allowed’ to use, but if you are Ltd Co that problem goes away. It really used to piss me off that an agency could effectively tell me who my employer should be.
Yes, it’s all about back handers and agreements between the agencies and the ltd companies.
Some agencies even have their own umbrella companies and push you through there, making money out of the recruitment and the payroll.
Back in the day as a recruitment consultant, umbrella companies used to offer incentives to me to put people through them. If you got ‘X’ amount of contractors you’d get this or that. The more you got, the bigger your gift. They ranged from Supercar driving days to holidays in Florida..i kid you not.