One in four students do not complete Year 12 and nearly 15 per cent of high schoolers fail to turn up each day, undermining attempts to lift Australian education outcomes and prompting calls for mental health screening programs.

The retention problem is greatest in government schools, where just 73 per cent of public school students complete Year 12, down from 79.8 per cent in 2017, compared to 87.2 per cent in non-government schools, according to a new report from the Productivity Commission.