From the first line in the article
Inland Revenue is giving hundreds of thousands of taxpayers' details to social media platforms for marketing campaigns
I'm not sure from this wording, if this means that FB et al are requesting the data for their own advertising campaigns; or the IRD are using these platforms to advertise.
"The lists uploaded monthly are for things like student loans where the overseas-based customer population is constantly changing with people moving overseas or returning home."
Implies that the IRD is the one advertising. But then it goes into hashing, if the data is anonymized; how is the data used to target for example, the delinquent SL borrowers?