The utility companies accused of wrongly charging customers at a higher GST rate say they haven't done anything wrong.
Revenue Minister Peter Dunne has criticised Genesis, Meridian and Auckland Metrowater for charging the new GST rate of 15% - which took effect on 1 October - for September power or water use.
Mr Dunne says the companies concerned chose to ignore a transitional provision included in the GST act precisely to deal with such a situation.
Genesis, however, says it obtained advice on the application of the transitional rules to its business and followed that advice.
Meridian and Auckland Metrowater both say that any bill dated 1 October or later, and sent on or after that date, has to have the new GST rate of 15%, rather than the old rate of 12.5%.
Mr Dunne has called on the companies to act in good faith and credit the overcharged GST on customers' next accounts.
He says people should check their bills and contact their suppliers if they are being unfairly charged the higher rate of GST on their September consumption.