Census 2018 has counted 4.7 million kiwis, but there will be no iwi affiliation information presented.
Government statistician Liz MacPherson says, "It’s a significant loss and one of the things we're doing is working closely with iwi and Māori organisations on how to meet their data needs."
Attempts to find alternative government data sources to compensate also failed to fill the gaps because they either do not collect the information or what is collected does not meet required standards.
Te Ao Māori News asked Minister for Statistics James Shaw if this represented a failure by government.
He says, “Iwi affiliation data has never been terribly good and that is something the chief statistician has said she really wants to rectify.”
"We are looking at other agencies, for example, to collect iwi affiliation data where they hadn't previously got it so that over time we do build up a much more accurate iwi affiliation count."
In a pre-budget announcement this afternoon, Shaw allocated $6mil to fix issues arising from the 2018 Census and a further $10mil to prepare for the 2023 Census. He did not know how much of this money would go towards improving iwi affiliation counts.
Treaty law expert Dr Carwyn Jones says a lack of this data could impact Crown Treaty settlement offers and asset management because claimant group size is a factor.
"Obviously if there is not sufficient information about [iwi affiliation] that can affect the offers that groups get in settlements, but also there’s a question around how information that is collected by government, or ought to be collected by government, is used by Māori and iwi groups themselves in terms of how they target their energy and resources."
Figures were expected to be released for some topics including Māori electorate counts in September.
The 2018 Census was the first to be conducted online in a digital-first model, but this is being independently reviewed after criticisms about not catering efficiently for households without internet and a low turnout. The report is due next month.