Coromandel, Waihi, and Whangamata BNZ branches will be closed by June 2021, and the Katikati branch by the end of March 2021.
BNZ chief customer officer Paul Carter said Covid-19 had accelerated trends the bank had been seeing for some time, with customers increasingly choosing to do their banking online.
Changes to its branch network are part of a wider review of all BNZ locations to consolidate its workforce.
"We don't take this decision lightly. We made our commitment on regional branches in good faith. Not only was it a commitment to the communities we serve, it was also a commitment to our people, as closing a branch used to mean losing jobs.
"However, Covid changed everything. Our customers have embraced digital services and tools and our bankers are serving customers irrespective of where they are. We've shown we can work from anywhere and there are job opportunities for all our people - it reflects the ongoing shift in how our customers are choosing to bank with us."
The closures will mean customers must travel to Whitianga from Coromandel Town, to Thames from either Waihi or Whangamata - and Katikati residents must drive to the Cameron Rd branch in Tauranga.
The decision - part of nationwide closures of branches by the BNZ - is being hailed as "disappointing" by groups such as Grey Power, which has active memberships throughout the Coromandel, and will be "strongly objecting to this action".
They say it will impact on the Coromandel's elderly population but also the whole community in places such as Whangamata where the bank has been a huge support.
Waihi Grey Power has more than 400 members. Margaret Sole, speaking as a resident of Waihi, said many Waihi people were reluctant to use technology and were still concerned about not being able to use cheques.
"I don't know what they'll do, a lot of people don't drive, they just walk up the street."
However BNZ says bankers are often waiting in empty branches for customers that do not arrive.
In the last six months, around 300 people have used the Coromandel branch, 400 the Katikati branch, and 500 the Waihi and Whangamata branches, on more than one occasion, BNZ figures reported.
The bank says each location will keep a Smart ATM for withdrawals, deposits and transfers.
Coromandel Member of Parliament Scott Simpson says the Coromandel was unique because of its demographic of retirees and remoteness for online services.
"While I accept more and more customers are banking digitally, it is sad to see the closure of these branches across our area. These branches were staffed by locals who personally knew their customers.
"BNZ advise that they will help their customers with the transition. This is absolutely necessary as we have a higher proportion of people aged over 65 and in some places around the Coromandel access to the internet is not available or very limited.
"Moreover, some people simply prefer to do their banking in person. This decision removes their ability to choose and it follows hard on the heels of the removal of chequing facilities.
Unfortunately the days of knowing your banker are coming to an end.
Grey Power Whangamata said BNZ staff have gone out of their way to help older residents adapt to the digital era.
"We are sorry that their expertise will now be lost to us," said Cushla Jervis, who was awaiting for an official response from Grey Power's national body.
She said community groups will also suffer as many of these rely on raffles to support them.
The Coastal News reported how a Whangamata retiree lost his entire life savings to a scammer posing as a Spark representative before staff at Whangamata BNZ were able to track it down and retrieve the money.
"Thank god for the bank, otherwise we would have been penniless," said the 75-year-old who did not want to be named, embarrassed at being caught out.
"They took in the vicinity of $20,000," he said.
The fraudster claimed to be calling from Spark and got the man to start up his computer, asking him questions and getting him to open his emails and his online banking.
"Because we've been with [BNZ] so long they thought it strange that all this money was going overseas and stopped it," he said.
"We are just so lucky that the girls at the bank are so well trained [on signs to look out for with fraud].
"This is the beautiful part of having a personalised bank, if they took our bank away from us I'd be devastated because they know us. We were one of the lucky ones."
The local BNZ branch brought in a national fraud expert at the time, Bronwyn Groot from CFFC, to Whangamata for a free and interactive workshop that was booked out by locals needing get savvy on scams.
Whangamata BNZ manager Jennie Boland said last year frauds had become rife in town and the staff worried about their customers.
"Some of them are very vulnerable, especially the older ones who seem to be very trusting."
Jennie reported at the time that some customers were so vulnerable to scams that the bank had decided to refuse to send money or had blocked large transactions by these customers.