Asic has accused banks of “not getting the basics right”, after the regulator found faulty mortgage offset accounts meant borrowers were being overcharged tens of millions of dollars in extra interest payments. A borrower with an outstanding loan of $100,000 and $20,000 in a properly linked mortgage offset account, for example, should only be paying interest on $80,000. In one case, a bank accidentally unlinked a customer’s offset account when processing a change to their mortgage. “When offset accounts don’t operate correctly, the harm can be hidden. Of the 204,000 home loans, Asic found issues with hundreds of mortgage offset accounts.