Westpac-owned mortgage broking franchise RAMS Financial is under investigation and may face penalties related to home loans written over four years in which franchisees may have flouted credit rules, including around responsible lending.

An Australian Securities and Investments Commission review of the group and its franchisees has been under way since at least September, accounts filed to the corporate watchdog show, after internal reviews identified “prior issues that have the potential to impact our customers and our reputation”.