Intellectual Disability Diagnostic Assessment (IDDA)

An Intellectual Disability Diagnostic Assessment (IDDA) is a series of questions to help your clinical person understand what your experience is.


The doctor or specialist will take the answers and use them to make an assessment, diagnosing whether someone has an intellectual disability or if there’s something else they may need support with.

Having this diagnosis will helps health professionals understand the kind of supports you or your loved one might need to live a good life.  

What is an intellectual disability in New Zealand? 

You or a loved one might be seen as experiencing an intellectual disability if: 

  • there are difficulties which have been around for a long time in keeping up with and responding to the demands of everyday life 

  • help is needed with basic independent living skills  

  • a good amount of support is required to help with learning due to significant difficulties 

Why get an IDDA? 

An IDDA gives a formal diagnosis of an intellectual disability which is required if your needs mean that it would be helpful to access support from Disability Support Services. Support could be money for equipment, education support, in-home support or residential care services.  

What does an IDDA involve? 

The IDDA typically includes: 

  • the assessor gathering information about your medical, educational, and developmental history 

  • looking at how you react and experience different settings (like with family or at school) 

  • psychometric testing – tests that help understand how you think, learn, and behave 

  • a final report to the person who referred you with their findings and recommendations 

The assessment process itself generally takes three to four hours of contact time, although you may need to take additional time to complete various questionnaires. 

How to get an IDDA 

You’ll probably visit your doctor or hospital first and in your appointment they might make the suggestion to look at an IDDA. They might refer you to an occupational therapist or a NASC provider (Needs Assessment and Service Coordination). They will refer you for the IDDA if they believe you might have an intellectual disability. 

People aged 17 and above can get an IDDA through NASC. For those under 17, the assessments will be done by Child Development Services. These could be through a paediatrician, child and adolescent mental health services, or at school.   

After an assessment is made, the report will be sent to your NASC person or your local Child Development Service, and you are able to ask for a copy of it from them. 

Find out more about the Needs Assessment and Service Coordination (NASC) process here

Who does adult IDDAs? 

Explore Wellbeing is a nationally contracted provider for IDDAs for people aged 17 and above. They will be the organisation that NASCs make referrals to. At Explore, these assessments have a limited wait time as clinicians are available across the country. There is no cost for an IDDA.  

To find out more about what they do, you can call Explore on 0800 605 001 or email explore@explore.org.nz.   

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