The Spring bank holiday – on May 4 – will see more than a hundred branches open to the public for the first time.
Royal Bank of Scotland (RBS) and NatWest have announced they will open 34 branches across the UK as part of a trial.
Rival Barclays typically opens between 40 and 50 branches every bank holiday.
And Metro Bank said every one of its 34 branches will be open as usual.
RBS said it was opening its busiest branches in cities including London, Edinburgh, Manchester and Newcastle.
It said there was significant demand on a bank holiday from customers who want to discuss mortgages, or other banking matters.
“Many of our customers have busy lives, but are off work on a bank holiday,” said Jane Howard, managing director of branch and private banking for RBS and NatWest.
“At a time when many people are thinking of buying a house, we’re breaking with tradition and opening our busiest branches,” she said.
Three other banks – HSBC, Lloyds Banking Group and Santander – said they had no plans to open on bank holidays.
The Bank Holidays Act was originally passed by parliament in 1871, initially guaranteeing four bank holidays, on top of Good Friday and Christmas Day.