There are 2 ways for a New Zealand citizen to enter the United States for tourism or business:
ESTA visa (Electronic System for Travel Authorization) is an application system for all travellers from US Visa Waiver Countries to enter the United States without a visa.
Approved ESTA APPLICATIONS are valid for a period of two year unless the passport expires earlier. When traveling to the U.S. with an approved travel authorization, you are allowed to stay for maximum 90 days at a time.
Citizens of New Zealand will generally receive an approved ESTA application that is valid for two years. Short-term visitors to the US (those staying for less than 90 days) can simply apply for the authorization without going through the tedious process of a visa application.
Remember, however, that the ESTA grants only eligibility to travel visa-free. Your entry is still determined by the immigration officer in your port of entry.
The requirements for ESTA are fewer compared to the visa application process. You only need the completed online application form, your machine-readable passport and credit card for the processing and payment of your application submission. You do not need to show other details such as your hotel or flight reservation. Other details of your itinerary can be finalized upon approval of your authorization or at any point before departure.
Only citizens of USA Visa Waiver Countries are allowed to apply for ESTA. It is important to know if you are qualified for ESTA before you even submit your online application. The ESTA application system is entirely online. There are no forms that need to be printed and you do not have to go to a U.S. Embassy or Consulate in person. Find out if you are qualified to use the Electronic System for Travel Authorization.