This figure does not include those who were approved for residence but never arrived.
The Ministry of Business, Innovation and Employment, which oversees immigration, said the factors underpinning New Zealand's loss are "not yet well understood", but international research indicates that failure to find a job and fit into the host society are among the reasons why migrants leave.
Massey University Associate Professor of Marketing Henry Chung believes that despite being absent, these migrants could still be worth millions to the New Zealand economy and a study to understand the "absent migrant economy" was desperately needed.
Dr Chung said most of the absent migrants were from countries with economies performing better than New Zealand, and believed the low wages, high taxation and a lack of opportunities may be some of the factors why they left.
"New migrants bring business ideas from their home countries here, starting Asian supermarkets and importing products from Asia to have a point of difference," he said. "Returnee migrants leave with a New Zealand connection and will be bringing Kiwi business concepts and products back home."
He gave the example of Suncern in Taiwan, a business started by returnee migrants.
"This is a famous shop operated by immigrants who returned to Taiwan and specialises in selling goods and products imported from New Zealand," Dr Chung said. "It's a win-win situation, good for both New Zealand and the returnee, and very successful because of their sound knowledge of New Zealand, its products and the Taiwanese business environment."
Dr Chung believed a significant number of the returnee migrants have come from the business categories, and a significant number would still have business links and investments in New Zealand.
"They are an asset, and understanding this absent migrant economy could unleash huge business and marketing opportunities."
Since July 2009, 185 applications had been approved under the investor categories, with almost $520 million placed in complying investments, and 176 applications approved in principle to invest with an investment value of nearly $480 million.
Another 210 applications, valued at $395 million, were currently being processed.
Migrant Ken Mar, who has returned to Singapore, said he still considered New Zealand his "first home".
"I had to return to Singapore to look after my aged parents, I'm their only child and they cannot acclimatise to the New Zealand weather," Mr Mar said. "When they pass on, I'll go back to New Zealand for sure."
He learned taxidermy in New Zealand and now operates a taxidermy business in Singapore.
"I currently source all my taxidermy supplies from New Zealand, such as skins and forms for use in my current business," Mr Mar said.
Mr Mar, who is a member of the New Zealand Taxidermy Association, said he still had investments in New Zealand but would not reveal how much.
However, an immigration adviser said some of his absent clients had wanted residency mainly to get their children into New Zealand schools.
New Zealand was one of just a few countries that offered "indefinite" residency, and migrants who qualified need not spend a fixed amount of time here to maintain their status.
"So these residents are holding to their residency as a retirement option, while leaving their children here to complete their high school or university education," said the adviser, who did not want to be named.
A 2010 University of Auckland study, entitled "Homeland on the move: New Chinese immigrants to New Zealand as transnationals", found many Chinese considered New Zealand migration to be a stepping stone to get to other Western countries, such as Australia.
Massey University sociologist Paul Spoonley said migration patterns were now "more fluid" and it was unrealistic to expect migrants to remain in one country permanently.
"We are recruiting migrants who are better educated and with wealth, and this is a group that's extremely mobile," Professor Spoonley said. "They will leave if they find that New Zealand does not meet their expectations, and go where the better opportunities are."
Absent migrants
Top 10 nations (for those approved for residence between 2004-2011):
• United States 2,479 (27 per cent)
• Taiwan 265 (26 per cent)
• Singapore 349 (25 per cent)
• Canada 762 (25 per cent)
• Netherlands 549 (21 per cent)
• China 8,257 (20 per cent)
• Indonesia 247 (20 per cent)
• Germany 927 (19 per cent)
• Malaysia 817 (19 per cent)
• France 282 (17 per cent)
• Total (all countries) 40,692 (14 per cent)
Source: Immigration New Zealand
