NZ vs AU: Understanding Tax Obligations When You Operate Across the Tasman

For many New Zealand businesses, Australia represents the most natural market for expansion. The shared language, cultural similarities, and geographic proximity make it feel straightforward. But beneath the surface, the tax systems of the two countries diverge in ways that can catch business owners off guard, and the consequences of getting it wrong range from unexpected tax bills to penalties and double taxation.

Who Needs to Worry About Cross-Border Tax?

If you are a New Zealand resident who earns income from Australian sources (whether through a branch office, contracts with Australian clients, an Australian subsidiary, or even rental property), you likely have tax obligations in both countries. The same applies in reverse: Australian residents earning New Zealand-sourced income will have filing obligations here.

It is not just large corporates that face this issue. We regularly see sole traders, freelancers, and small companies with trans-Tasman clients who have never considered whether they need to register for GST in Australia, file an Australian tax return, or apply for relief under the Double Tax Agreement (DTA).

Key Differences Between the NZ and Australian Tax Systems

Tax Year

New Zealand's standard tax year runs from 1 April to 31 March. Australia's runs from 1 July to 30 June. This mismatch alone creates complications for businesses operating in both jurisdictions, particularly around timing of income recognition and deductions.

GST Thresholds and Rates

New Zealand's GST rate is 15% with a registration threshold of $60,000 in turnover over a 12-month period. Australia's GST rate is 10% with a registration threshold of A$75,000. If you are making taxable supplies in Australia, you may need to register for Australian GST separately, even if you are already registered in New Zealand. The rules around what constitutes a taxable supply in Australia differ from New Zealand, so do not assume your New Zealand GST knowledge transfers directly.

Entity Types

While both countries have companies, partnerships, and trusts, the tax treatment varies significantly. Australia does not have an equivalent of New Zealand's Look-Through Company (LTC). Australian trusts are taxed differently from New Zealand trusts, particularly following New Zealand's trust tax reforms. If you are considering setting up an entity in Australia, take advice on the most appropriate structure before you incorporate. Restructuring after the fact is far more expensive.

Company Tax Rates

New Zealand's company tax rate is 28%. Australia's base rate is 30%, though small businesses with aggregated turnover below A$50 million may qualify for a reduced rate of 25%. The imputation systems in both countries work similarly in principle but differ in detail, and franking credits from one country cannot be used in the other.

Common Pitfalls

Double Taxation

The Australia-New Zealand DTA exists to prevent the same income being taxed twice. However, relief under the DTA is not automatic. You typically need to claim it, and the mechanism differs depending on the type of income (business profits, dividends, royalties, employment income, and so on). Many business owners assume they will not be taxed twice without actually checking whether they have claimed the appropriate relief.

Residency Rules

Tax residency in both New Zealand and Australia is determined by a range of factors, not just where you live. New Zealand uses a day-count test (183 days in any 12-month period) alongside a permanent place of abode test. Australia has its own residency tests, including the domicile test, the 183-day test, and the superannuation test. It is entirely possible to be a tax resident of both countries simultaneously, which triggers additional reporting obligations.

Withholding Tax on Cross-Border Payments

Payments such as dividends, interest, and royalties flowing between New Zealand and Australia may be subject to withholding tax. The DTA reduces the standard rates, but you need to ensure the correct rate is applied and that the appropriate IRD or ATO documentation is in place. Non-resident withholding tax (NRWT) in New Zealand and withholding tax obligations in Australia are areas where we see frequent errors.

Transfer Pricing

If you have related entities on both sides of the Tasman, you need to ensure that transactions between them are priced at arm's length. Both the IRD and the ATO take transfer pricing seriously, and the documentation requirements have become more stringent in recent years. Even relatively simple arrangements, such as a management fee charged by a New Zealand parent to an Australian subsidiary, need to be commercially justifiable and properly documented.

When to Get Specialist Advice

The honest answer is: before you start operating across the Tasman, not after. We regularly work with clients who have been trading in Australia for years without realising they had unfiled obligations. Sorting out historical non-compliance is always more costly and stressful than getting the structure right from the outset.

You should seek specialist trans-Tasman tax advice if you are:

• ●Setting up a new entity or branch in Australia (or New Zealand, if you are Australian-based)
• ●Sending employees to work across the Tasman, even temporarily
• ●Earning income from clients or customers in the other country
• ●Receiving dividends, interest, or royalties from across the Tasman
• ●Considering relocating personally while retaining business interests in your home country
• ●Unsure whether you have existing unfiled obligations in either country

The cost of a proper cross-border tax review is modest compared to the cost of getting it wrong. Penalties, use-of-money interest, and the sheer administrative burden of unwinding years of non-compliance are far greater.

“The cost of a proper cross-border tax review is modest compared to the cost of getting it wrong.”