Failure to address educational inequalities in England means taxpayers have to "pay twice", says an alliance of 25 education organisations.
Unless every child gets a fair chance, the cost of schooling is followed by more expense later, it says.
The Fair Education Alliance sets out five national targets to break what it calls "the class ceiling".
Education Secretary Nicky Morgan said the government wished to ensure all pupils achieved their full potential.
The report, Will We Ever Have A Fair Education?, says educational unfairness starts before children even start school, with poorer five-year-olds less ready for learning than their more affluent peers.
The Fair Education Alliance was launched in June, with 25 organisations including businesses, education charities, trade unions and campaign groups pledged to work to "significantly narrow the achievement gap between young people from our poorest communities and their wealthier peers by 2022".