Background: Dedifferentiated policy treats adults with intellectual disabilities as part of the larger group of people with disabilities. The implications of the dedifferentiated National Disability Insurance Scheme (NDIS) for adults with intellectual disabilities are explored. Methods: Analysis of peer reviewed and grey literature between 2014 and 2020 about design of the NDIS and outcomes. Results: Many participants experienced problems with NDIS implementation. Outcomes for adults with intellectual disabilities compared poorly to other groups. They were disadvantaged by standardised planning processes relying on self-expressed needs and omission of supported decision making. As the NDIS matures, it is becoming more differentiated but issues relevant to adults with intellectual disability remain largely invisible. Conclusions: Further shifts towards standardised planning and functional assessment may be disadvantageous for adults with intellectual disabilities for whom support needs are dependent on social and contextual factors, and exercise of choice on support for decision making.