Under the Admission to Schools Bill, it's expected that schools will only be able to allocate 10 percent of places for children of past pupils.
Clonmel High School was involved in a high profile admissions case when Mary Stokes took a case on behalf of her son John after he was refused admission to the school.
She claimed the school policy of giving preference to the children of past pupils indirectly discriminated against Traveller children.
The Supreme Court ultimately ruled this was not the case.
Minister Jan O'Sullivan will announce details of the Bill when she addresses the INTO conference in Co. Clare later today.
All primary and secondary schools will be obliged to comply with the new rules.
