The notes are printed on paper which can tear easily as opposed to legal tender which is printed on polymer.
When accepting cash retailers are advised to take a "look, feel and tilt" approach to identify a genuine banknote.
Information on this can be found on the Reserve Bank of NZ website.
If you find you've already received a counterfeit banknote, put it in an envelope to avoid handling it further, and get in touch with Police.
Anyone with information about the manufacture or distribution of counterfeit banknotes is asked to contact Police on 105.
Information can also be provided anonymously through Crimestoppers on 0800 555 111.