NZ Carers Alliance chairman John Forman said the carers who qualified were in many cases also the disabled person's parent - putting the decision-making on the shoulders of a person who may be severely or profoundly disabled.
It would introduce an employment aspect into the relationship, which could sour the family dynamic, he said.
The disabled person would also have to oversee compliance tasks such as ACC levies and Kiwisaver contributions.
"In addition, there are so many service and compliance layers that it will cost a fortune to monitor.''
The best that could be said of the scheme is that there are 1600 carers who will be paid the minimum wage for some of their work, he said.
It was a "cheap and dirty'' response to a major social policy issue, and a raw deal for carers and those they support, Mr Forman said.
"A more workable solution would have been for family carers to be paid directly by the Government as independent contractors.
"This would have been far more practical, and respectful of the carer and the disabled person,'' he said.
The scheme comes into effect on Tuesday.