Te Tari Taiwhenua / The Department of Internal Affairs (DIA), is the public service department of New Zealand charged with issuing passports; administering applications for citizenship and lottery grants; enforcing censorship and gambling laws; registering births, deaths, marriages and civil unions; supplying support services to ministers; and advising the government on a range of relevant policies and issues.

Other services provided by the department include a translation service, publication of the New Zealand Gazette (the official newspaper of the New Zealand Government), a flag hire service, management of VIP visits to New Zealand, running the Lake Taupo harbourmaster's office (under a special agreement with the local iwi) and the administration of offshore islands.

The Department of Internal Affairs traces its roots back to the Colonial Secretary's Office, which from the time New Zealand became a British colony, in 1840, was responsible for almost all central Government duties. The department was the first government department to be established in New Zealand, and it became the home for a diverse range of government functions providing services to New Zealanders and advice to Ministers of the Crown. Hence the title of Michael Bassett's 1997 history of the department: The Mother of All Departments.

Many of these responsibilities were lost as new departments and ministries were formed. The office's name was changed to the Department of Internal Affairs from 19 November 1907. Change has continued to the present day, as new roles and functions have come into the department and others have been transferred elsewhere

sourced from https://en.wikipedia.org/wiki/Department_of_Internal_Affairs_(New_Zealand) and https://www.dia.govt.nz/ 2 Sept 2021