The government needs to find an extra $1 billion in Thursday's Budget to ensure every child has the support they need to learn, teachers say.
Primary and early childhood teachers union the Educational Institute commissioned independent economists to calculate how much money would be needed to restore past spending, after cuts, and cope with growing demands.
Infometrics said almost half the extra money required, $425 million, was needed to ensure proper support for children with special needs.
Union president Lynda Stuart said New Zealand's primary education funding was well below the OECD average.