If you find this confusing: how does my child transition from Early Childhood Early intervention(ECEI) to the NDIS? Well, that is because it is confusing. Here are some ideas on how to navigate this transition, with some useful links:

1. Starting point might be to call the NDIS on 1800 800 110 and ask about your specific situation.  If you get no joy from this try the next steps.
2. ECEI is for children 0-6 showing any sign of developmental delay. The ECEI pathway was implemented to give a 'broader gateway' - but it also acts as a 'filter' for full NDIS eligibility.
3. We need to remember that NOT every child who shows a developmental delay in childhood goes on to get a formal diagnosis (and get support from the NDIS in the future).  
4. Your Early Childhood Access Partner should assist in helping you to determine eligibility for ongoing support from the NDIS.
5. In order to transition from ECEI to NDIS participant, the person will need to meet NDIS eligibility criteria via either Section 24 (Disability) or Section 25 (Early Intervention)
6. Know your ASD level in accordance with the DSM5. It is specifically mentioned that ASD level 2 & 3 are granted access with 'no further assessments required'.  Deductively that would suggest that ASD level 1 will need to provide some sort of extra justification to determine eligibility.  Exactly what will depend on your circumstances, but we can assume that the NDIA will be looking for evidence of functional capacity across the domains of communication. social interaction, learning, mobility, self-care and self-management.  

Here are some useful links relating to Section 24 and Section 25 NDIS Eligibility criteria as well as the "definition" of Autism:

1. Access to the NDIS - disability requirements (section 24)
2. Access to the NDIS - early intervention requirements (section 25)
3. The disability criteria for 0-7 years
4. Disability criteria for 7-65 year
5. Here is the early intervention criteria
6.   'List A' (most likely to meet NDIS eligibility criteria)
7. Per list A it describes Autism as 'Autism diagnosed by a specialist multi-disciplinary team, pediatrician, psychiatrist or clinical psychologist experienced in the assessment of Pervasive Developmental Disorders, and assessed using the current Diagnostic and Statistical Manual of Mental Disorders (DSM-V) diagnostic criteria as having severity of Level 2 (Requiring substantial support) or Level 3 (Requiring very substantial support)'