The following discusses the practical advantages of New Zealand citizenship for permanent residents and Australian citizens in New Zealand.
Over and above the most important reason, which is a sense of commitment and belonging to your adopted home.
- Retaining residency and avoiding deportation
It is true that permanent residents (with an Indefinite Returning Resident visa) and Australian citizens do not lose the right to return to New Zealand after an extended absence overseas. However, this could be changed by a future government.
Becoming a citizen is the only way to guarantee you have the right to remain in New Zealand
Permanent residents and Australian citizens are at risk of losing their status in New Zealand if they commit certain crimes. The citizenship of a naturalised New Zealand citizen cannot be revoked for any crime committed after becoming a citizen.
Only New Zealand citizens have the right to own certain categories of rural property.
- Immigration for family members
As at March 2009, there is no significant preference for citizens over settled permanent residents in the sponsorship process. However, this could change.
One difference which does persist is that New Zealand citizens can sponsor spouses for migration while living outside New Zealand. Under the law, permanent residents and Australian citizens are expected normally to be "usually resident" in New Zealand.
- Running for political office
Many types of elected positions require the officeholder to be a New Zealand citizen.
Most New Zealand government jobs are open to permanent residents, but some, especially at policy and management levels, may require the applicant to be a New Zealand citizen citizen.
If a security clearance is needed, with citizenship you can have a higher level, but don't forget that having ties to the UK via friends, family, property etc might still limit the level of clearance you may gain.
As a New Zealand citizen you are entitled to an New Zealand passport (which may have better visa-free travel) and to consular protection from New Zealand missions overseas. However, New Zealand consular protection is not normally available in any other country of which you are a citizen.
Having a second passport is more convenient if you need to send one away to be renewed, have a visa placed in it, etc.
- Citizenship for non-New Zealand born children
As a naturalised New Zealand citizen you will be able to register children born to you outside New Zealand (born after you become a citizen) as New Zealand citizens by descent. See also: New_Zealand_Citizenship_by_Descent
A New Zealand passport gives residence rights in Australia, although with restrictions. See also New_Zealanders_Rights_in_Australia.
If you are a citizen of a non-Commonwealth country, and have a United Kingdom born grandparent, becoming a New Zealand citizen will mean you are likely eligible for the British Ancestry Visa.
New Zealand citizens can use a more advantageous working holiday visa program in Canada, compared to that for British citizens (and many others).
New Zealand citizenship gives you the right to represent New Zealand in international events. If you are not a New Zealand citizen, you may still be eligible, depending on the sport and the specific competition (for Olympic events, citizenship is always mandatory).
Access to New Zealand funding for elite sport development may be more difficult if you are not a New Zealand citizen.
It may be more difficult to adopt a child in New Zealand if you are not a New Zealand citizen.
Citizens of some countries may lose their existing citizenship upon becoming New Zealand citizens, which may or may not be a problem. British citizens do not lose citizenship upon becoming New Zealand citizens. Some holders of other kinds of British nationality may encounter issues.
Australian, Canadian and American citizens do not lose citizenship upon becoming New Zealanders.
If you keep your former nationality, the Embassy of your home country will no longer be able to intervene on your behalf with the New Zealand authorities (since they can't get you out of jail anyway, this is a limited benefit).
You are obliged to serve on a jury, if called upon.
 Not impacted
The following are generally not impacted by becoming an New Zealand citizen, if one is already a permanent resident:
There is no impact on your New Zealand tax obligations, under current law.
Becoming a New Zealand citizen does not in itself' impact the ability of a permanent resident to access British pension entitlements.