A Work to Residence visa is something migrants on temporary work visas would need if they want to permanently live in New Zealand. Once you have this, you will automatically gain the formal status of a resident, and you will be allowed to stay in the country indefinitely. Of course, you will also be given access to various publicly funded services. Before you become a resident, however, you would need to be eligible first.

Basic Requirements
There are a few ways to qualify for a work to residence visa, but the basic requirements for them remain the same. Fulfilling these should be your first priority. Firstly, you must have a valid passport with an expiry date not exceeding three months past the date when you have to leave New Zealand. It’s also required to have been working for at least two years and to be under the age of 56. Next are good health, good character and a genuine desire to work in the country. The visa you used to enter New Zealand should also be in the right category.
Upgrading Visas
Upgrading from other types of work visas to acquire residency is arguably the easier route to take if you are planning on a long-term relocation. This is because you will be readily welcomed as a valuable member of the workforce. There are two ways to be eligible for a work to residence visa, and both can be achieved through upgrading current work visas.
If you qualified for a Long Term Skill Shortage List work visa, you can apply for residence provided that you meet basic requirements and ones that are specific for this category. For instance, you must have been employed full time for occupations that can be found on the Long Term Skill Shortage List for the duration of your 2-year stay. You should also be currently employed while on the process of getting residency and have base salary of NZ$45,000 per year. If applicable, migrants should also have full or provisional registration to practice in their respective occupations.
For those with temporary work visas under the Accredited Employers Category, the same basic eligibility requirements should be followed. Full time employment by an accredited employer for two full years is also a must. For this category, you should be earning at least NZ$55,000 a year.
So long as you meet all the requirements, there’s a good chance that you will be approved for residency. Still, it would be far easier to work with an NZ immigration adviser if you want to avoid any hassles.
Sources:
Residence from Work Category, New Zealand Now
The Work to Residence programme, Workingin-NewZealand.com