13.—(1) Subject to regulations 11 and 12, a local education authority may, in determining budget shares for schools which they maintain, take into account in their formula, as they consider appropriate, any or all of the factors or criteria set out in the Schedule, as provided for in the Schedule.
(2) A local education authority must, in determining budget shares for both primary and secondary schools which they maintain, take into account in their formula a factor or factors based on the incidence of social deprivation among pupils registered at all such schools.
(3) A factor included in an authority’s formula pursuant to paragraph 19 of the Schedule is not, for the purpose of paragraph (2), a factor based on the incidence of social deprivation among pupils registered at a school.