The Australian Securities and Investments Commission has approved rule changes that allow the Australian Financial Complaints Authority (AFCA) to investigate matters dating back to 2008.

From next month, consumers and businesses can lodge complaints about conduct in that time period.

AFCA has a 12-month window to investigate such complaints, which must not have been dealt with by its predecessors or any court or tribunal.

CEO David Locke says the authority has identified thousands of complaints that could be submitted, based on cases lodged but deemed outside the jurisdiction of previous schemes.

“There will also be many matters that were never lodged with the Financial Ombudsman Service, the Credit and Investments Ombudsman or the Superannuation Complaints Tribunal that may now be brought to us,” he said.

“We also expect that these matters are likely to be highly complex, and further complicated by the number of years that have passed since the issue occurred.”

The Government extended AFCA’s remit by 12 months earlier in the year, with Treasurer Josh Frydenberg saying it will help more people harmed by financial misconduct.

Previously, AFCA could only investigate complaints from the past six years, or two years if the matter had been through a company’s dispute resolution process.