Legislative frameworks in England have been designed to support children with special educational needs and disabilities (SEND). Despite efforts from policy makers, achievement gaps persist between students with SEND and their typically developing peers. This study examines the extent and persistence of academic achievement gaps between students with various SEND classifications and their peers. Utilising data from the National Pupil Database, a comprehensive analysis of approximately 2.5 million Year 6 students across four academic years was conducted. The analysis focused on reading, mathematics, and writing achievements, exploring variations by SEND type and assessing changes over time. The findings revealed substantial, persistent gaps across all examined subjects, with the largest discrepancies noted in students with intellectual disabilities. Although some variability was observed based on the type of SEND, all students with SEND performed, on average, below their peers, with gaps widening over the examined period. The results underscore the need for a critical re-evaluation of educational practices and policies intended to support students with SEND.