In 2003, the Department for Education in England commissioned research which supported the policy drive to reduce the reliance on statements for special educational needs (SEN). Twenty years on and the government's emphasis has now switched from reducing workload to creating financially sustainable systems. There continues to be wide variations in local authority (LA) statutory assessment practice, with considerable differences in the proportion of pupils with education, health and care plans (EHCPs), even when benchmarked across demographically comparable authorities. LAs with low EHCPs have smaller high needs block (HNB) budgets but typical rates of special needs and disability (SEND) Tribunal appeals. A comparison is also made of the statutory assessment process within the four nations of the UK. The discussion considers the implications of the findings for sustainable high needs systems and for appropriately managing the demand for EHCPs. The current 25-year trendline is projecting towards 10% EHCPs by 2042, a remarkable increase from 2.5% in 2017.