More than 10,000 children left school in one year and local authorities admit they have "no idea" where they are, according to a new report by the Children's Commissioner.
Over 12 months from spring 2022, 10,181 children left state education with no known destination, while another 13,120 moved to home learning - with many parents reporting this was a "last resort".
Figures also show 2,868 children were either known or suspected to be out of education completely.
These so-called "ghost children" - more of whom have been reported since the pandemic, as Sky News has revealed - are more likely to be from deprived areas and be known to social care.
"I am deeply concerned to see just how many children are falling through the cracks after leaving the state-funded education system," Children's Commissioner Dame Rachel de Souza said.
"While the reasons for leaving school may vary, my report highlights that thousands of children are simply unknown to local authorities."
Analysis of the data found most of the children who left state education to go to home education were aged 11 to 14 (64%).
Most who had unknown destinations were aged four to nine (54%), as were many of those known to be, or suspected of, missing education (41%).
Most parents interviewed for the report said they chose home education as a last resort, claiming schools had not offered the support their child needed to engage in education.
More than 80% of all children who moved into home education were persistently or severely absent in the previous year.
"I have spoken to thousands of children who have told me about how important school is for them, but this report shows too many young people are finding themselves out of education," Dame Rachel added.
