The Northland Rugby Union says a decision by the New Zealand Rugby Union to cut it from the Air New Zealand Cup is flawed and unconstitutional.
Both Northland and Tasman will be axed from the first division in a move to streamline the national provincial competition.
The Northland union was scored poorly on financial and governance issues in a review by the NZRU.
The union admits it had a tough year, but says it's pulling itself out of the hole without any significant financial help from the NZRU - unlike other unions.
It has set up an advisory group headed by former Northland prop and All Black manager Richie Guy to improve governance and financial management.
A new board and chair will be elected in October and it has already found an experienced new chief executive.
Submissions on the review closed on Friday.
Chairman Wayne Peters says Northland is confident it can present a comprehensive financial plan for the next three years.
Nelson Bays is also lodging an appeal to keep Tasman in the first division.
The NZRU board will make a final decision at the end of September.