Westpac Banking (ASX:WBC, NZE:WBC) will allow home loan customers to set up up to 10 offset accounts with no additional fee, according to a Monday release from the financial services firm.

"An offset account is an everyday bank account linked to your home loan, where every dollar in your account reduces, or offsets, the interest you pay," said Damien MacRae, Westpac's Managing Director of Mortgages.

The bank observed a 37% increase in offset accounts opened over the past five years, as well as a 63% increase in offset account balances over the same period.

Westpac research found that 71% of Australians who have an offset account with their mortgage use it to reduce their home loan.

Multiple offset accounts are already available to customers of St.George, Bank of Melbourne, and BankSA.

Westpac's shares fell 4% on market close.