Police are warning retailers about an increase in the number of counterfeit notes being used.
North Island shop-owners are reporting people buying items with fake $20, $50 and $100 bills and collecting legitimate money in change.
Police say with the busy Easter period approaching retailers should stay vigilant about what is being handed to them.
Shop-owners are advised that if someone tries to use a fake note they should consider refusing to take it, and then pass a description of the fraudster to the police.
Police urged retailers to check the Reserve Bank's tips on how to spot a counterfeit.