More than 150 people are expected to attend a celebration to mark his 50th anniversary on October 9, including some who he had worked with since 1970.
He has now worked with four generations of the Brownrigg family.
"That's the big thing, clients become more than clients, they become friends."
Epplett said it had always been the plan, when he set up his own business (Epplett and Co) in 2002.
"My philosphy, when I created the practice, was basically we are not out just to make every last dollar. We do a lot of voluntary community work and community work. Our theme was accountants with heart, and that's been the ethos of the firm I created."
He was also the Bishop of Palmerston North's representative on the Catholic Education Management Board and on the Mission College Napier Trust Board.
In 1989 he took on the government over its funding for schools, something he was still proud of.
"I suppose some of the things that during that period that have been stand out things for me was one when I took on the Minister for Education on schools.
"We did a three-year survey, wrote to all the schools in New Zealand. I had over 200 schools' financial results for three years and basically proved at that stage to the government that parents were funding about a third of expenditure.
"That report got published nationwide - that was a very big thing for me because I like to think it made a difference and helped get some increased funding for schools."
His dedication to the industry was recognised recently with a Fellowship from Chartered Accountants Australia and New Zealand.
Looking to the future, Epplett said he expected to see the day when chequebooks no longer existed.
"I can see that the accounting process is going to become even more streamlined. That's already happened with Xero, and that's something I predicted a few years ago would happen."
He also hoped the government's latest working group around tax would come up with ways to improve New Zealand's complicated tax system.
"I suppose the simplification of the tax system is something I would like to see."