The Commissioners running the Kaipara District say they believe the rates struck by the council were lawful and must be paid.
A legal opinion sought by the leaders of the Mangawhai rates rebellion suggests the rates are invalid because the council failed to follow the statutory process in setting them.
It says errors include the failure to produce an annual report beforehand and to consult the community again about changes to the long-term plan.
The chairman of the Kaipara commissioners, John Robertson, says he does not believe any irregularities in the council's processes invalidate the rates, but the commissioners will be happy to consider the legal opinion and review their position.