Instagram is about to change dramatically for teenagers, with the platform introducing automatic "teen accounts" for underage users in Australia, the US, the UK, and Canada.

Teen accounts will come with content restrictions, new rules about who can contact those users, and features designed to curb screen time.

Instagram's parent company Meta said the changes would apply straight away for new accounts, while the company is aiming to switch existing teenage users to the tighter rules within 60 days.

Meta's announcement comes a little over a week after the federal government revealed it would seek to enforce a minimum age for social media before the end of the year, but the company says the timing is not linked.

"It's going out now because it's ready now, but it's been upwards of a year since we started working on it," head of Instagram Adam Mosseri said.

"I can't spend a bunch of time trying to design a product with my team that is going to appease a group."

What will change for Australian teenagers and their families?

Mr Mosseri said parents, rather than governments, were their "north star" in developing teen accounts.

"One of the things we heard loud and clear from parents in the research was they didn't want to have to figure it out, they wanted it to work without them getting involved," he said.

For that reason, he said, teen accounts will be automatic, rather than opt-in.

Sixteen and 17 year-olds will have the power to opt out of the most restrictive settings, but anyone 15 or younger will need a parent or guardian's permission to do so.

Meta said the same rules would be introduced on its other platforms next year.

Meta’s plan to stop teenagers from dodging the changes

Meta said it was fully expecting many teenagers would try to evade the new measures.

"The more restrictive the experience is, the stronger the theoretical incentive for a teen to try and work around the restriction," Mr Mosseri said.

In response, the company is launching and developing new tools to catch them out.

Instagram already asks for proof of age from teenage users trying to change their listed date of birth to an adult one, and has done since 2022.

Now, as a new measure, if an underage user tries to set up a new Instagram account with an adult date-of-birth on the same device, the platform will notice and force them to verify their age.

In a statement, the company said it was not sharing all the tools it was using, "because we don't want to give teens an instruction manual".

"So we are working on all these tools, some of them already exist … we need to improve [them] and figure out how to provide protections for those we think are lying about their age," Mr Mosseri said.

The most stubborn category of "age-liars" are underage users who lied about their age at the outset.

But Meta said it was developing AI tools to proactively detect those people, by analysing user behaviour, networks and the way they interact with content.

Australians won't see that technology for some time though — it was expected to be trialled with US users in 2025.

"There's no perfect solution," he said.

"It would be amazing if we could catch 70 per cent of teens with 70 per cent accuracy," he said.

He said while it was possible to verify ages across the board, "we are talking about collecting people's biometric face data or government IDs … these are very sensitive pieces of information that I would rather not collect".

Will it hurt Instagram’s bottom line?

Meta described the measures as the industry's strongest to date, and it was aware there may be a price tag.

Mr Mosseri said he hopes his competitors follow their lead, but believes some companies "won't make the changes unless they are forced to".

He expected the changes would drive some teenagers away and onto other platforms in the meantime.

"We are definitely going to see loss of teen engagement and teen growth … the question is how much, not if.

"I have to assume it's good for our business over the long run … but it's going to be difficult and it's going to hurt in the short run."