Hundreds of voting papers for a referendum on fluoride have had to be sent to voters in the Hastings district after they were omitted from local body voting packs.
Last week, the Auckland Council admitted mistakes had been made in some of its material.
A Wellington law firm is now offering a reward for the person who finds the highest number of local body election booklets with mistakes.
The mayor of Hastings District Council, Lawrence Yule, says the council discovered the mistake on Friday.
He says the council had to manually identify the 500 affected residents and then mail them the correct papers.
Mr Yule - who is also the president of Local Government New Zealand - says it was an issue with the way data had been set up in the computer system, as opposed to a mistake by the returning officer.
