The policy, due to take effect on 10 December, will require social media companies to take “reasonable steps” to stop Australian children from creating accounts and to deactivate existing ones.
Ministers say the measure is intended to reduce the harmful impacts of online platforms on children, and it has been described as a world first that is being closely monitored by governments abroad.
The federal government asked the UK-based Age Check Certification Scheme to examine how the ban could be implemented.
Its final report assessed a variety of approaches including parental approval, the use of government documents, and age estimation based on facial features, gestures or behaviour.
The new report said: “But we did not find a single ubiquitous solution that would suit all use cases, nor did we find solutions that were guaranteed to be effective in all deployments.”
Identity document verification was found to be the most accurate method, but researchers warned platforms could retain the data longer than necessary or share it with regulators, leaving users exposed to privacy risks.
Australia has suffered several high-profile data breaches in recent years, with stolen personal information sold or published online.
The study found facial assessment technology was 92 percent accurate for users aged 18 and over but far less reliable for those around the age threshold.
It said the “buffer zone” – two to three years either side of 16 – could lead to false positives allowing children onto platforms, or false negatives excluding legitimate users.
Parental approval methods also raised privacy and accuracy concerns.
It recommended layering multiple approaches to create the most robust system, and noted technology providers were already working on ways to address circumvention, such as forged documents or VPNs that hide a user’s location.
Communications minister Anika Wells said: “There was no one-size-fits-all solution. The report showed age checks could be private, efficient and effective.
“These are some of the world’s richest companies. They are at the forefront of AI. They use the data that we give them for a bevy of commercial purposes.
“I think it is reasonable to ask them to use that same data and tech to keep kids safe online.
“There is no excuse for social media platforms not to have a combination of age assurance methods in their platforms ready for 10 December.”
Companies face fines of up to A$50 million (£25.7 million; $32.5 million) if they fail to comply with the ban.
Facebook, Instagram, Snapchat and YouTube are among the platforms affected.
Polling suggests most Australian adults back the measure, though some mental health advocates argue it could isolate young people or drive them towards less-regulated parts of the internet.
Others have called instead for stricter policing of harmful content and better education to prepare children for online life.
