NZTA permits holders of a foreign licence to drive for a period of up to 12 months in New Zealand. After 12 months you will need to transfer your licence to a NZ licence.
However, if you do not have an international licence, and your licence is not in English, then you must carry an English translation of your licence issued by an approved translator.
If you do not carry this translation, along with your original licence when driving, if you are stopped by the police you may not be allowed to continue driving.
Also, if you want to rent a car, campervan etc. then you will need the licence translation, as this is the only way the rental car company can check what class of licence you hold.
For further more detailed information please visit the NZTA website. www.nzta.govt.nz