Filing your IR3 as a sole trader is more involved than an employee’s tax return — you must declare all business income, claim allowable expenses, and complete an IR10 financial statements summary if your turnover exceeds $35,000. This step-by-step guide walks you through the full process.
File your IR3 by 7 July (or 31 March with a tax agent). Declare total business revenue, deduct allowable expenses to get net business income, and add any other income (interest, wages). Complete an IR10 if turnover is over $35,000. Pay any terminal tax by 7 February. Most sole traders use accounting software (Xero, MYOB, Hnry) to prepare their numbers before filing via myIR.
Before You Start: What You Need
Gather these before logging into myIR:
Income records:
- Total invoices issued / payments received (business income)
- Bank statements confirming income received
- Employer earnings summary (if you also had PAYE employment)
- Interest certificates from banks
- Any dividends received
Expense records:
- Receipts and invoices for all business expenses
- Vehicle logbook (if claiming vehicle costs)
- Home office calculations (floor area × eligible costs)
- Asset register (for depreciation calculations)
Other:
- Previous year’s IR3 (for comparison and prior year figures)
- Any provisional tax instalments paid (visible in myIR)
- Student loan balance (if applicable)
- KiwiSaver contribution amount (voluntary contributions)
Key Deadlines
| Deadline | Date |
|---|---|
| Tax year end | 31 March 2026 |
| IR3 due (self-filers) | 7 July 2026 |
| IR3 due (with tax agent) | 31 March 2027 |
| Terminal tax due (standard) | 7 February 2027 |
| Terminal tax due (with tax agent) | 7 April 2027 |
| Provisional tax 1st instalment (2026–27) | 28 August 2026 |
Step 1: Calculate Your Business Income
Add up all revenue received from your business during the tax year (1 April 2025 – 31 March 2026). This includes:
- All invoices paid by clients
- Cash receipts
- Payments in kind (valued at market value)
- Cancelled debt (if a client’s debt you wrote off is later paid)
If you are cash basis (most sole traders are), you report income when you receive it, not when you invoice. If you choose or are required to use accruals basis (required if turnover exceeds $5 million), you report income when it is earned.
Step 2: Calculate Allowable Deductions
Subtract your allowable business expenses from gross income. Common categories:
| Category | What to include |
|---|---|
| Cost of goods sold | Stock purchased for resale |
| Vehicle | Logbook % of costs, or 25% flat, or mileage rate |
| Home office | Floor area % × rent/rates/insurance/interest/power |
| Equipment (under $1,000) | Full cost in year of purchase |
| Depreciation | On assets over $1,000 |
| Subcontractors | Amounts paid to subcontractors for work |
| Professional fees | Accounting, legal, consulting |
| Software and tools | Business subscriptions |
| Marketing | Advertising, website |
| Training | Directly related to current business |
| Insurance | Business-related insurance premiums |
| Bank fees | Business account fees |
| Interest | On business borrowings (not private debt) |
Net business income = Gross revenue − Total allowable expenses
This net figure is what flows into your IR3 as taxable business income.
Step 3: Complete the IR10 (If Required)
If your business turnover exceeds $35,000, you must complete an IR10 (Financial Statements Summary) as part of your IR3 filing. The IR10 captures:
- Total income (broken into categories)
- Total expenses (broken into categories)
- Net profit / loss
- Key balance sheet figures (assets, liabilities, equity)
You do not need formal financial statements — the IR10 is a simplified summary. However, you need your totals to be accurate and categorised.
IRD uses IR10 data to check that income and expenses are being reported reasonably. Significant anomalies (e.g., expenses that are 95% of income when your industry average is 60%) may trigger a review.
Step 4: File Your IR3 via myIR
- Log in at myir.ird.govt.nz
- Go to Income tax → File a return
- Select the 2025–26 tax year
- Review pre-populated data (wages, interest — check these are correct)
- Enter business income and expenses
- Complete the IR10 if required
- Enter other income (rental, interest if not pre-populated)
- Claim any tax credits (donations, IETC if applicable)
- Confirm student loan details if applicable
- Review the summary — myIR calculates tax automatically
- Submit
Step 5: Review Your Tax Outcome
After submission, myIR shows:
If you have a refund: Accept it and nominate your bank account. Typically paid within 5–10 business days.
If you have terminal tax to pay: This is the balance of tax owed after your provisional tax payments are credited. Due by 7 February 2027 (or 7 April with a tax agent). Pay via:
- myIR (bank card or direct debit)
- Internet banking (use IRD’s bank account and your IRD number as reference)
- At a Westpac branch
If you have a large terminal tax bill: This is common in the first year of self-employment (no provisional tax paid). In subsequent years, you will be on provisional tax which reduces the year-end shock.
Common Mistakes to Avoid
1. Not separating business and personal bank accounts Commingling funds makes it difficult to identify business income and expenses. Open a dedicated business account before you start trading.
2. Forgetting to include cash income All income is taxable, including cash payments. IRD can compare your declared income to your bank deposits.
3. Claiming personal expenses as business Claiming meals, holidays, or personal purchases as business expenses is one of the most common audit triggers. Apply the “wholly or partly for business” test honestly.
4. Missing depreciation Many sole traders either forget to depreciate assets or try to write off large assets in one year. IRD requires assets over $1,000 to be depreciated at set rates.
5. Not keeping records Without records, you cannot prove your deductions. Keep all receipts and invoices for 7 years.
6. Missing the filing deadline A late IR3 results in immediate penalties. File on time even if you cannot pay the tax — late payment is better than late filing because the penalties differ.
Should I Use Accounting Software?
For most sole traders with more than minimal activity, accounting software significantly reduces compliance time and risk:
| Tool | Best for | Approximate cost |
|---|---|---|
| Xero | Growing businesses, multiple income streams | $35–$85/month |
| MYOB | Small businesses, inventory | $27–$65/month |
| Hnry | Freelancers and contractors (manages all tax) | 1% of income, capped at $1,500/year |
| Wave | Very simple businesses, minimal transactions | Free |
Hnry is worth mentioning specifically for NZ freelancers: it calculates and pays your tax in real time, handles GST, files your IR3, and manages provisional tax — all for a 1% fee.
Frequently Asked Questions
Do I need a separate bank account as a sole trader?
It is not legally required, but it is strongly recommended. A separate account makes it simple to identify business income and expenses, which is essential for accurate tax filing.
Can I file a paper IR3?
Yes, but myIR is significantly faster and allows IRD to pre-populate your data. Paper returns must be sent to IRD and are more likely to contain errors. Use myIR wherever possible.
What if I made a loss?
If your business expenses exceeded your business income, you have a business loss. This loss can be offset against other income (wages, rental income) to reduce your total taxable income. If you have no other income, the loss carries forward to future years.
I have both a job and a side business — how do I file?
You use tax code M for your main employment, and your employer deducts PAYE. You declare your employment income on your IR3 (pre-populated by IRD) and also declare your business income and expenses. The combined income is assessed at your correct marginal rate.