Extra money for poorer pupils should be paid to schools and colleges until they are 18, say head teachers.
They want the next government to extend the pupil premium throughout sixth form, from the present cut-off of 16. Schools and colleges in England are given extra funding for children from disadvantaged homes.
In a manifesto school heads say the pandemic and the cost of living crisis have widened the gap between wealthy and poorer children.
The Association of School and College Leaders (ASCL) wants the premium to be weighted so pupils in persistent poverty attract a higher premium.
The union wants an extension of the free schools meals scheme and auto-enrolment for all families on universal credit.