The Government has admitted it has no idea how much it will cost taxpayers to roll out a flag change if the alternative option wins the referendum.
Newshub can reveal Finance Minister Bill English has not established the costs of changing the flag on official material such as police uniforms, driver's licenses and navy ships.
"It's hard to say -- there's been some work done on it we haven't gone into huge detail," Mr English said when asked about the cost.
The only concrete figure Mr English can provide is $2.7 million to replace about 1500 flags on government buildings and to update Defence Force uniforms.
A spokesperson for Mr English said this figure was just for flags and did not include the cost of changing badges, lapel pins and pennants for official vehicles. Departments would have to meet the cost out of existing budgets.
The spokesperson also confirmed there were no costings for changing a number of other flags and ensigns that are based on the current New Zealand flag -- such as the police and the Fire Service.
"Other costs, including changing flags on Government ships and on drivers' licences, will be confirmed after the referendum, but these changes will happen over time," the spokesperson said.
"The NZ Transport Agency will take a practical approach and is likely to incorporate a new flag in driver's licences at the time of individual licence renewal, after the date on which the new flag becomes the official flag."
The spokesperson said the Government would not be changing the New Zealand Coat of Arms, even though the current flag features prominently.
Mr English also revealed if there was change, it would not automatically include flags that carry the Union Jack and that he did not expect them to change.
That means the Union Jack would remain on a number of different flags and ensigns.
"The other agencies that have their own flags don't have to change anything because it's their flag, they decide what to do with it, that's not what's being voted on," Mr English said.
"Where the armed forces have their own flags, they keep their own flags, that's up to them to decide what to do. I assume they'll just keep their flags because the public's not voting to change the armed forces flag, we're voting on the New Zealand flag."
New Zealand First Deputy Leader Ron Mark said Mr English was hiding the true cost.
"The interesting thing is the Minister of Finance with all the resources of treasury, the Minister of Economic Development, these guys have the staff, the resources to know exactly what that cost is and they should come clean with the public," he said.
"New Zealand First has always said we believe that the total cost of a flag change with all of the trickle down effects would be 50 million and we can only just ballpark that."