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This paper discusses alternative methods to estimate the distribution of wealth in New Zealand. It develops a taxable income capitalisation method for estimating the distribution of wealth in New Zealand that is based on the approach of Saez and Zucman (2016; 2022) and adapted for New Zealand data sources, which we term “the New Zealand capitalisation method”. Internationally, taxable income capitalisation has been found to be a high-performing method for estimating asset holdings that generate taxable income flows, particularly towards the top of the wealth distribution where household surveys often undercount wealth. The New Zealand capitalisation method combines Inland Revenue taxable income administration data with Stats NZ’s Household Balance Sheet to give new estimates of the distribution of New Zealand individuals’ wealth. We present results for 2010, 2015, and 2018, and compare these distributions with those recorded by the Household Economic Survey (HES) 2018. Our method also allows for wealth estimates of smaller groups than can be reliably obtained through HES, including estimates of the wealth held by the top 0.1% of the wealth distribution. The New Zealand capitalisation method suggests more wealth at the top of the distribution than estimated by HES, which is consistent with similar work internationally. Results also show that wealth shares at the top of the distribution fell between 2010 and 2018, while at the same time the greatest increase in average wealth went to the top of the distribution.
The views, opinions, findings, and conclusions or recommendations expressed in this working paper are strictly those of the author(s). They do not necessarily reflect the views of the New Zealand Treasury or the New Zealand Government. The New Zealand Treasury and the New Zealand Government take no responsibility for any errors or omissions in, or for the correctness of, the information contained in this working paper. The paper is presented not as policy, but with a view to inform and stimulate wider debate.
These results are not official statistics. They have been created for research purposes from the Integrated Data Infrastructure (IDI) which is carefully managed by Stats NZ. For more information about the IDI please visit https://www.stats.govt.nz/integrated-data/. The results are based in part on tax data supplied by Inland Revenue to Stats NZ under the Tax Administration Act 1994 for statistical purposes. Any discussion of data limitations or weaknesses is in the context of using the IDI for statistical purposes, and is not related to the data’s ability to support Inland Revenue’s core operational requirements.
We acknowledge Sean Comber at Inland Revenue for helpfully and efficiently programming and running our many capitalisation variants.
We also acknowledge our many colleagues within and outside the Treasury for their input and support with this work, including Stephen Bond, Patrick Nolan, Philip Vermeulen, Robert O’Hara, Shane Domican, Margaret Galt, John Marney, Robert Templeton, Michelle Griffin, Mike Webb, Rupert Crispin-Morrall, Lindsay Beck, Jason Fullen, and Mario DiMaio.