Mr Shepherd said NRC would also appeal an earlier decision by the High Court on how it set due dates for the payment of rates and its arrangements for rate collection within Kaipara.
He said at the heart of the case, which had implications for local authorities nationally, was NRC's use of Kaipara District Council to collect rates on its behalf.
"While appealing will be costly, the council feels the issues at stake are too important not to appeal. The collection of rates by the district councils in the region on behalf of the regional council provides significant cost savings which benefit the region's ratepayers."
Mr Shepherd assured ratepayers NRC had not acted irresponsibly or blatantly flouted the law.
In addition to the appeal, NRC will also approach the Department of Internal Affairs asking it for a law change clarifying the section of the Rating Act covering rates collection arrangements.
NRC chief executive Malcolm Nicolson said his council was talking to other territorial authorities in Northland about consolidating all four councils into a single rating unit.
That will mean one entity sending out rates invoices to all ratepayers in Northland in a bid to cut costs.
On legal costs, Mr Nicolson said NRC had a special budget of $200,000 per year and it was confident of using the remaining funds to cover the Court of Appeal case rather than having to set aside more money.
He said the councillors would be informed at their next meeting of the estimated cost of the appeal.
Mangawhai Ratepayers and Residents' Association chairman Bruce Rogan said the appeal was a gross waste of ratepayers' money.
Mr Rogan, his wife Heather and the association were parties to the judicial review hearing in the High Court.
He said the winning parties in the High Court would have to find $50,000 to $60,000 to fight the appeal.
In 2013 when ratepayers appealed an earlier High Court ruling, Mr Rogan said, the former chairman of commissioners at Kaipara District Council, John Robertson, said court judgments should always be accepted.
"Not so, it seems, when the judgment is in favour of the community and not to the liking of the Government," Mr Rogan said.