Peter Thiel, the controversial US tech billionaire granted citizenship in 2011, had only spent 12 days in the country.
Usually, new citizens have to spend at least 1350 days out of a five-year period here to be eligible.
Mr Thiel, who co-founded Paypal in 1999, had only been in New Zealand four times in his life before he applied for citizenship. The Department of Internal Affairs confirmed in February he was granted citizenship in 2011, but didn't say how long he'd spent here.
That information has now been released after advice from the Ombudsman.
He applied for an exemption from the usual rules, citing his entrepreneurial skills and philanthropy. He said at the time he had no intention of living here. He owns a 193ha estate near Lake Wanaka.
Before being granted citizenship, he told former Internal Affairs Minister Nathan Guy he had met with former Prime Minister John Key, current Prime Minister Bill English and former Minister of Economic Development Gerry Brownlee, as well as prominent business leaders, including Sam Morgan and Rod Drury.
Mr Thiel is worth more than US$2 billion. He bought a 10 percent stake in Facebook in 2004 for US$500,000, which netted him a US$1 billion payday in 2012 when he sold his shares.
Mr Thiel is an outspoken supporter of equally controversial US President Donald Trump.
Mr Thiel has also invested around NZ$50 million in accountancy software company Xero and the New Zealand Venture Investment Fund.
"I'm very comfortable with the decision I made in 2011" - Minister
The Minister who signed off on giving Mr Thiel New Zealand citizenship in 2011 is backing his decision.
"I've been back and reviewed the file, I completely agree with the officials at the time that he should have been granted citizenship under exceptional circumstances," Nathan Guy told media on Thursday.
"This guy has made a significant investment here in New Zealand.
"This is an individual who is incredibly well connected in Silicon Valley. He's a great ambassador and salesperson for New Zealand.
"The New Zealand media are only really interested in this issue because of his connection to the Trump regime."