GST shouldn't be used as a tool to change behaviour.

There's an idea from Sir Michael Cullen's tax working group that GST could be lowered if it recommends new environmental taxes - such as on petrol, water consumption and waste sent to landfills.

But Deloitte tax partner Allan Bullot told Mike Hosking the Government should be careful with GST.

"If you start to use GST as a tool to change people's behaviour for healthy eating and stuff like that, you are then starting to ask the tool to do more than it was originally designed for."

LISTEN TO ALLAN BULLOT TALK WITH MIKE HOSKING ABOVE