Of the more than 3 million Australian households that have a mortgage, more than half feature an offset account.

When used appropriately, these accounts can save borrowers thousands annually by applying additional savings to reduce the outstanding balance on a home loan, thereby lowering interest costs.

There is some $300 billion sitting in offset accounts across Australia.

However, 9News has uncovered that the Australian Securities and Investments Commission (ASIC) is worried that customers might not be receiving these intended savings due to bank mistakes.

“We’ve heard, in some instances, the banks have not connected the offset account to someone’s mortgage account,” commissioner Kate O’Rourke said.

“That’s bad for the consumer, but we’re not sure how widespread that problem is.

ASIC has initiated a monitoring program involving eight banks, including some from the big four, and it has suggested that reimbursements might be forthcoming if it discovers that customers have been deprived of their entitled savings.

“Our expectation is that when things have not been properly done, consumers are remediated,” O’Rourke said.

The program could take a year to find out how many people have been impacted.

Meanwhile, consumers are advised to meticulously review their statements and seek confirmation from their bank that their accounts are correctly linked, should they have any concerns.