An independent panel to investigate super-city options for the Wellington region will be formed on Wednesday afternoon.
Wellington Regional Council and Porirua City Council will vote on the panellists, who will consult the public on different governance models and recommend the one they think is best.
The cost of the panel, originally budgeted at $150,000, is now more than $240,000.
Councils throughout New Zealand are reviewing their structure as part of a Government drive to make them more transparent and financially efficient.
The seven other Wellington councils are also carrying out public consultation. All councils will make a submission to the Local Government Commission by the end of the year.