My gift voucher expired before I could use it

Expiry terms are not banned in New Zealand, but they must be clear, fair and disclosed properly. If the expiry date was not shown on the voucher and you were never told of it when it was bought, the business may be engaging in misleading conduct under the Fair Trading Act 1986, and the term itself may be open to challenge as unfair if it forms part of a standard form contract. Ask the business in writing to honour the voucher, explaining that the expiry was not brought to the purchaser's attention. Ask the person who bought it to keep their purchase receipt and any confirmation email. Many businesses will honour or extend a voucher when politely challenged. If not, you can raise it with the Commerce Commission or make a claim in the Disputes Tribunal.