Do Aussies need a passport for NZ?

Yes, Australian citizens do require a valid passport to enter New Zealand. While Australia and New Zealand have a close bilateral relationship, and Australian citizens are granted certain privileges when traveling to New Zealand, such as being able to enter without obtaining a visa in advance, a valid passport is still a mandatory travel document. For Australian citizens, your passport just needs to be valid on both your departure and return date. For Australian permanent residents travelling on another country's passport, the passport needs to be valid for at least 3 months after your return date from New Zealand.