About 7.9 million people had their drivers licence details taken, with 3.2 million, or 40 per cent of those numbers, provided to the company in the last 10 years.
53,000 passport numbers were stolen.
Fewer than 100 customers had a monthly financial statement stolen, the consumer finance company told the ASX on Monday.
Latitude admitted in the statement that an additional 6.1 million records dating back to at least 2005 were also poached in this month's hack, including names, addresses, telephone numbers and dates of birth.
"We recognise that today's announcement will be a distressing development for many of our customers and we apologise unreservedly," the company said.
"We are writing to all customers, past customers and applicants whose information was compromised outlining details of the information stolen and our plans for remediation."
Latitude will reimburse customers if they choose to replace their identity document, the company said.
""It is hugely disappointing that such a significant number of additional customers and applicants have been affected by this incident," CEO Ahmed Fahour said, pledging a full review into what occurred.
He warned customers now need to be extra careful with cyber security.
"We urge all our customers to be vigilant and on the look-out for suspicious behaviour relating to their accounts. We will never contact customers requesting their passwords, "he said.
"We continue to work around the clock to safely restore our operations. We are rectifying platforms impacted in the attack and have implemented additional security monitoring as we return to operations in the coming days."
Latitude disclosed on March 16 that a few days earlier it had detected a "sophisticated and malicious cyber-attack" on its systems, but at the time thought it involved hundreds of thousands of customer records, not millions.
Opposition spokesman for cyber security, Senator James Patterson tweeted it is distressing news for Latitude's customers.
" The government must swiftly provide calm, factual information about the implications of the attack and any steps customers should take to mitigate the threat," he wrote.
The Australian Federal Police is investigating and the company is working with the Australian Cyber Security Centre and outside advisers.
