Children and teenagers will be banned from using social media from the end of next year after the government's world-first legislation passed the parliament with bipartisan support.

That means anyone under the age of 16 will be blocked from using platforms including TikTok, Instagram, Snapchat and Facebook, a move the government and the Coalition argue is necessary to protect their mental health and wellbeing.

The late vote capped off a frantic day in the Senate, where the government managed to ram through most of its legislative agenda on the final sitting day of the year.

Coalition senators Matt Canavan and Alex Antic crossed the floor to vote with the entire crossbench against the laws, which received mixed reviews from mental health experts during a snap Senate inquiry this week. Liberal Richard Colbeck abstained.

It followed an hour of spirited debate that saw crossbenchers question and heckle the major parties over what they said was a rushed and flawed law.

Liberal MP Bridget Archer also broke with her party earlier in the week to vote with the Greens and a handful of independents against the bill in the House of Representatives on Wednesday.

The major parties had moved quickly to pass the legislation before the end of the parliamentary year, despite reservations from some Coalition MPs, the Greens and independents who called for more time and greater scrutiny.

Tech companies also agitated for the debate to be delayed until the government's age-verification trial is finalised.

Under the laws, which won't come into force for another 12 months, social media companies could be fined up to $50 million for failing to take "reasonable steps" to keep under 16s off their platforms.

There are no penalties for young people or parents who flout the rules.

Social media companies also won't be able to force users to provide government identification, including the Digital ID, to assess their age.

"Messaging apps," "online gaming services" and "services with the primary purpose of supporting the health and education of end-users" will not fall under the ban, as well as sites like YouTube that do not require users to log in to access the platform.

The bill was introduced to parliament last Thursday and was referred for a Senate inquiry the same day. Submissions to the inquiry closed on Friday, a three-hour hearing was held on Monday, and the report was tabled on Tuesday.

Almost all the submissions raised concerns about the "extremely short" consultation period, the committee report noted.

"Legislation is a necessary tool, but it is not a panacea," Labor senator Karen Grogan wrote.

"Young people, and in particular diverse cohorts, must be at the centre of the conversation as an age restriction is implemented to ensure there are constructive pathways for connection."

During the public hearing, witnesses with experience working with young people on their mental health offered a mix of views on the ban.

Danielle Einstein, a clinical psychologist who has supported the campaign to raise the age at which kids can access social media, said social media offered no mental health benefits for young people as far as she could see.

But Nicole Palfrey from mental health organisation Headspace was more circumspect, telling the inquiry there was a need to balance any harms from social media with the benefits of connection and "help-seeking" online — especially for kids who live in remote or rural areas.

"When we hear from psychologists and parents they are very much confronted with [the] pointy end, they only see the harms and I think that's incredibly valid," Lucy Thomas from anti-bullying organisation Project Rockit said.

"But as people working with young people every day, we also see the benefits.

"We need to tread very carefully or we risk dialling back young peoples' rights and pushing them into more isolated, less supported places."