The Prime Minister's unsuccessful bid to change the flag came in $4 million under budget, despite adding Red Peak at the last minute costing an extra $263,000.
The Department of Prime Minister and Cabinet has released the provisional breakdown of costs of the two flag referendums, which shows it cost $21.8 million, 15 per cent less than the budgeted $25.7 million.
Andrew Kibblewhite, the head of the Department of Prime Minister and Cabinet, revealed the final cost to a select committee this morning.
A full breakdown of the costs will be released this afternoon.
Mr Kibblewhite said about two-thirds of the money was spent on the referendum and the rest was for the Flag Consideration Panel.
The fees and travel of the Flag Consideration Panel of 12 well-known New Zealanders cost $284,000, well under the $465,000 budgeted.
They were paid a total of $162,000 in fees, spent $88,000 on travel, $24,000 on catering and $10,000 on miscellaneous costs.
Panel chair, Professor John Burrows, was paid $22,000 and the report noted many panellists, especially Professor Burrows, had not charged for a significant amount of their time.
Professor Burrows was entitled to claim up to $850 a day for his work, and the other panellists were entitled to $640 a day.
Fees ranged from $33,000 for flag historian Malcolm Mulholland to nothing for Xero boss Rod Drury, who declined any payment.
Beatrice Faumina claimed $7000 and most members claimed between $11,000 and $15,000.
Travel and catering costs related to 14 panel meetings and 25 roadshow events in the leadup to deciding the shortlist of designs for the first referendum.
Those roadshow meetings cost $200,000, including the cost of venue hire, catering, staff and rental vehicles.
They attracted significant criticism because of the low turnout, often in the single figures, and because they were held too early to allow for feedback on designs for the shortlist.
The cost of the flag process was criticised throughout and 57 per cent of New Zealanders voted to retain the current flag in the final referendum in March.
Forty-three per cent voted for the Kyle Lockwood design alternative.
Most of that was the cost to the Electoral Commission of running the two referendums, which cost $13.5 million, about $2 million lower than expected.
The first referendum cost $9 million and the second cost $6 million.
The next largest cost was the cost of public advertising and communication about the flag change process at about $4 million.
The figures show Parliament's decision to add Red Peak as one of the alternative flags after public pressure cost an extra $263,000, largely in the costs of reprinting brochures and advertising material to include it.
• Communications: $3.9 million
• Website/digital: $643,000
• Roadshow and other public meetings: $200,000
• Secretarial: $1.1 million
• Ministry of Justice policy/advice etc: $330,000
• First postal referendum: $9 million
• Second postal referendum: $6 million
• Admin: $109,000
• Total: $21.8 million