IRD number applications What is an IRD number? An IRD number is a unique number issued to you by Inland Revenue. Your number will be in the range of 10-000-000 to 999-999-999, so some people will have an 8 digit number and others a 9 digit number. Your number will never change, even if you move to another country and then return to New Zealand some time in the future. We do not reallocate old numbers or issue every number in the range. This ensures the uniqueness of every individual or organisation's number. Do I need an IRD number? You should apply for an IRD number if: you are earning an income you are starting a business you are registering for Working for Families Tax Credits you are registering for a student loan your child has a part-time job you file tax returns you ask us about your tax you apply for child support. It is not compulsory for every individual (eg baby, child) to have an IRD number, but if you or your children are earning income you have to pay tax. If you do not have an IRD number, tax will be deducted at a no-declaration rate, which is higher than the normal deduction rate. You can also apply for an IRD number for your child so a lower rate of withholding tax is deducted from interest earned on their bank balance. Important If you're registering for Working for Families Tax Credits you need to supply an IRD