Auckland Council is estimating the Occupy Aotea protest could cost ratepayers up to $200,000.
The group have been camping in Aotea Square for the past five weeks as part of a global protest movement.
Auckland Council has formally asked the protesters to leave the site and is threatening trespass notices if they ignore the request.
However police may not enforce such a trespass notice, due to Bill of Rights implications which they cited as a reason not to move protesters in Dunedin on.
Auckland Council said it has lost $8000 in revenue from cancelled events because of the occupation, has spent $20,000 a week on security guards, $500 a week on wire fences around the site, and another $60,000 will need to be spent on inspections of any potential damage caused to the waterproofing of the underground parking from tent pegs, Radio New Zealand reports.
If the protestors refuse to move on and the issue ends up in court, legal bills could be up to $40,000.
The protesters are due to meet tonight to discuss whether to move on before trespass notices are issued.
Meanwhile, the Occupy Wellington movement has issued a vision statement, in response to a request by the Wellington City Council, to set a date to leave Civic Square.
Instead of setting a date, the statement outlines problems in New Zealand identified by the group include the "widening gap between rich and poor, worsening child poverty, and widespread environmental degradation".
"Our vision is a genuinely sustainable system based on human values and the principles of real democracy, in which all planetary resources are treated as the common heritage of all the earth's inhabitants."