Your IRD number is a unique tax number given to you by the Inland Revenue Department of New Zealand. This number will be eight or nine digits long. If your IRD number is 8 digits, just add a ‘0’ to the front. If you don’t know your IRD number, it can be found here: https://www.ird.govt.nz/managing-my-tax/ird-numbers/find-my-ird-number