NAB will change its opening hours at 28 Victorian regional branches, including Castlemaine and Heathcote, from August 17.
Under the new model, 114 regional branches nationwide will see bankers split their time between over the counter service and digital or phone banking support, as more customers move online.
The branches in line for change will be open for customers from 9.30am to 12.30pm.
Outside of these hours, banks will support customers by phone and online chat.
NAB group executive personal banking Rachel Slade said it is clear the face of baking is changing.
"Our branches continue to be a really important part of many local communities, especially for local businesses," Ms Slade said.
"On average, a quarter of transactions take place between 9.30am and 10.30am in our regional branches."
NAB said more than 90 per cent of its customer interactions are now taking place online or by phone, with more than half of its customers logging onto NAB banking via its app or online each month.
Over the counter transactions reduced by a quarter in the past year, NAB said.
The Financial Sector Union has backed NAB's plans, which it says will keep jobs and branches open.
"270 staff work across these branches and the good news is that not one person will lose their job nor have any of their current hours cut and not one branch will close," the union said.
In March 2019, NAB chief executive Phil Chronican pledged to not close any regional bank branches until at least January 2021.
"We are proud of our heritage in regional and rural Australia and we want our customers to know that our priority is to serve them," Mr Chronican said.
The changes to branch opening hours come into effect on Monday, August 17.