The Ministry of Social Development says an investigation into how private information was accessed through public computer kiosks in Work and Income offices will also review the ministry's wider IT systems.
Sensitive information freely available through the kiosks was accessed last week by an IT analyst and a blogger who went public with the security breach.
The ministry has released the terms of reference for the inquiry, which chief executive Brendan Boyle says will review security around the kiosks to determine if any individual's privacy has been interfered with.
The inquiry will be done by Deloittes, with oversight by a steering group including the offices of the Privacy Commissioner and the Government's chief information officer.
An interim report is expected within the next two weeks.