The Acorn Foundation is celebrating its first 10 years this year and has grown from one donor fund in 2003 to 187 donor funds worth $8 million invested today.
The foundation works on an annual return-to-community rate of 5 per cent and will give about $400,000 to local community and charity groups this year.
But it will not be long until Acorn is annually giving 10 times that amount, founder Bill Holland said.
People throughout the district have written wills to include Acorn as a beneficiary of some portion of their wealth when they die, he said.
"If everybody dies tomorrow - which they obviously won't, I hope, because I'm one of them - we anticipate somewhere between $100 million and $150 million, which is huge."
But Mr Holland acknowledged most people leaving money to Acorn were aged over 60 and so it was conceivable most of the money currently anticipated would be earning returns for Acorn within the next 25 years.
This would put Acorn's returns to the community in the league of $5 million to $7.5 million annually, rivalling the annual community distributions of TECT (of which Mr Holland is a trustee).
The possibility of giving such huge amounts of money to the local community excites Mr Holland, who stressed Acorn was just an intermediary between the generosity of private individuals and collective community needs. "What is really exciting is if you're back here asking me in 10 years time 'how do I think the last 10 years have gone', at that stage we could well have $100 million, it's not beyond the realms of possibility.
"What I'm excited about is thinking about what is going to be happening ... how much our society can be improved over the next 10 years as the fruits are delivered."
Mr Holland returned this month from a five-week scholarship programme at the Centre of Philanthropy and Civil Society at City University of New York.
Philanthropy was a much more established tradition in the United States. Its government social welfare programme was not as extensive as New Zealand's, he said.
Mr Holland said he would like to see New Zealand culture change to champion generosity rather than attack the "tall poppies" who give to charity.
"I know a number of people who give a lot of money, but don't want their name to be given because the remarkable thing is they get knocked for doing it. When people give, for goodness sake, just be gracious.
"Just accept the gift and thank them, don't have a crack at their motivations."