In New Zealand you can't legally hire just anyone for certain work. A handful of trades are restricted by law because the risk (fire, gas, water, or a building that has to stand up) is too high to leave unregulated. Knowing which is which protects you, and it's easy to check.
Electrical work: the EWRB
Prescribed electrical work must be carried out by a registered and licensed electrical worker, or done under their supervision. That's true even for jobs that look small. Registration is held by the Electrical Workers Registration Board, and every licence can be looked up on its public register.
Plumbing, gasfitting and drainlaying: the PGDB
Sanitary plumbing, gasfitting and drainlaying must be done by someone registered and licensed with the Plumbers, Gasfitters and Drainlayers Board. Gasfitting in particular is life-safety work and never a DIY job, and the Board's register lets you confirm a person is current.
Structural building work: the LBP scheme
Restricted Building Work covers the structure and weathertightness of a home, and must be carried out or supervised by a Licensed Building Practitioner. For the primary structure and external moisture barrier, an unlicensed builder isn't just a risk; the work is non-compliant.
What isn't legally licensed
Plenty of good trades, including painting, tiling, landscaping and general property maintenance, aren't licensed by statute. Many still belong to voluntary bodies like Master Painters or the Roofing Association, which signal training and a standards commitment even where the law doesn't require one.
On The Contractor Hub, statutory licences carry a Verified badge and link straight to the public register, so you can confirm the credential before you make contact.