Ngai Tahu leader Mark Solomon says the few descendants who haven't enrolled on the iwi's whakapapa database prefer, as he does, to affiliate with the tribe they're mainly involved with.
Tribal membership has increased to 47,500 which means, based on 2006 census data, 96% of Ngai Tahu people are now signed up.
At 13,683, most Ngai Tahu live in Canterbury, with significant populations in Auckland - 5,739, Wellington at 4,944, Otago at 4,680 and Southland, where there are 4,632 Ngai Tahu descendants.
Mr Solomon, who is kaiwhakahaere of the iwi, says some Maori like him who can whakapapa to a number of iwi, choose to identify more strongly with the tribe they live or work with.
He says the few that haven't signed up are multi-tribal and prefer to align themselves with the iwi they have the most dealings with.
Mr Solomon says he attributes the high membership to the fact that Ngai Tahu has a big presence in the South Island, and the fact that it interacts with its members through the internet and media publications.
According to the 2006 census, 49,185 people identify themselves with Ngai Tahu.