An IR3 is the individual income tax return you file when IRD can't work your tax out automatically, which is almost always the case for sole traders, contractors and landlords. Here is what goes on it, when it is due, and how to file it without the usual headaches.
Quick answer
You file an IR3 when you have income that isn't fully taxed at source — self-employment, contracting, rental, overseas income, or business income through a partnership. You declare all that income, claim your deductible expenses, and the return works out your final tax. For most people it is due 7 July after the 31 March year-end, or the following 31 March if you are linked to a tax agent.
You can file it yourself in myIR, on paper, or have an accountant file it for you. The mechanics are not hard; getting the income complete and the expenses right is where the value (and the risk) sits.
The detail, in plain English
An IR3 brings together every kind of income you earned in the year:
- Self-employed or business income — your sales, less your business expenses.
- Salary or wages already taxed through PAYE (declared so the full picture is correct).
- Schedular payments with tax already withheld, plus the related expenses.
- Rental income, after allowable rental deductions and the ring-fencing rules.
- Interest, dividends and overseas income where relevant.
Against your business and rental income you claim deductible expenses — tools, a fair share of home and vehicle costs, ACC levies, software, professional fees and more. The return nets income against expenses, applies the right tax, credits anything already paid (PAYE, withholding, provisional tax), and lands on a refund or a bill.
A simple example
A contractor earns $80,000 gross for the year. He had $12,000 of legitimate business expenses, and $16,000 of tax was withheld from his schedular payments during the year.
| Line | Amount |
|---|---|
| Gross income | $80,000 |
| Less business expenses | $12,000 |
| Net taxable profit | $68,000 |
| Tax already withheld (credit) | $16,000 |
His tax is calculated on the $68,000 net profit, then the $16,000 already withheld is credited against it. Whether he owes a little or gets a refund depends on how his withholding rate matched his real position. The expenses he claimed knocked $12,000 off the income that gets taxed, which is exactly why complete records matter.
Common mistakes to avoid
- Missing income. Leaving off a bank interest line or an overseas payment is the fastest way to an IRD query.
- Under-claiming expenses. Many people forget ACC levies, home office, or vehicle costs and overpay tax as a result.
- Over-claiming private costs as business, which is the other side of the same coin and a common audit trigger.
- Forgetting provisional tax. A net profit over $5,000 of residual tax usually pulls you into provisional tax for next year.
- Filing late. Missing 7 July without an agent extension risks penalties and interest.
Where this fits in your return
The IR3 is the hub that everything else feeds into. Your GST returns run separately through the year, but your business profit lands on the IR3. Your provisional tax for the coming year is set from the residual tax this return produces. Your Working for Families entitlement is squared up against the income shown here. And your ACC levy is calculated from the business income you declare. Get the IR3 right and most of your other tax obligations fall into place; get it wrong and the errors ripple outward.
How Fernway can help
We prepare and file your IR3 end to end, making sure your income is complete, your expenses are claimed in full, and your provisional tax and ACC are flagged before they surprise you. If you are linked to us as your tax agent, you also get the extended filing time and a clear plan for any tax owing. Fixed fee, quoted up front, no hourly surprises.
This is general information, not personalised tax advice. Your situation may differ, so book a free review to discuss it with us or check ird.govt.nz.
This is general information, not personalised tax advice.See our full disclaimer.