Teenagers who are already on social media could be allowed to keep their accounts under the ban promised by the federal government.

Prime Minister Anthony Albanese opened the door to a softer ban, including the possibility of using parental permissions instead of a flat restriction, in a letter to state and territory leaders.

Mr Albanese wrote to premiers and chief ministers asking for assistance on setting up a minimum age to use social media, including any evidence they may have on what age the ban should lift.

The prime minister has previously expressed his preference that a social media ban be in place on the higher end of between 14 and 16.

South Australia had been developing a state-level ban that would have lifted at 14, while New South Wales Premier Chris Minns had advocated for the ban to lift at 16.

The SA's examination of a ban, which the prime minister has commended, would have restricted users 13 and under, and required parental consent for 14 and 15-year-olds to access social media.

"We know social media is doing social harm. We need to do everything we can to keep our kids safe and to help them grow up happy, healthy and confident," Mr Albanese said in a statement.

"Protecting children from harm is a shared responsibility across all governments, as well as industry, civil society and communities."

Alongside asking states for their views on grandfathering the scheme and "the role for parental consent to feature as a factor for age limits", Mr Albanese has asked for information on the need for exemptions, such as for educational tools, and an assessment of implementing phone bans in schools.

While the federal government has taken carriage of developing a social media ban, the states were asked what wrap-around measures they would provide to support young people, including alternate sources of social connection and supports for vulnerable people who may use social media as a particular source of connection.

In a sign the government is undecided as to whether young people already online should have their accounts taken from them, Mr Albanese also asked states for an assessment of the impacts of withdrawing those services from them.

Some social advocates have warned marginalised groups including sexually and gender diverse children could be left isolated without social media.

"Legislating a minimum age for social media access is about protecting young people, not punishing or isolating them," Mr Albanese said.

NSW and SA are due to jointly host a social media summit next week, which the prime minister will not be able to attend because he will be in Laos for for the Association of South East Asian Nations conference.