Residence Tie-Breaker Rules and the Substantial Presence Test: U.S.–NZ and U.S.–Australia Tax Treaties Explained

What is the Substantial Presence Test (SPT)?

The Substantial Presence Test (SPT) is the IRS’s primary method of determining when a foreign national becomes a U.S. tax resident.

You are considered a U.S. tax resident if:

1. You are physically present in the U.S. for 31+ days in the current year, and
2. Your weighted days total 183 days over a 3-year period:
   • Current year: count all days
   • First prior year: count ⅓ of days
   • Second prior year: count ⅙ of days

If you meet this threshold, you are treated as a U.S. resident for tax purposes—unless an exception or treaty tie-breaker applies.

Exceptions: Certain days don’t count toward the SPT (transit days, medical emergencies, students, teachers, and diplomatic exemptions). Additionally, if you spend fewer than 183 days in the U.S. during the current year and maintain a closer connection to another country, you can file Form 8840 to avoid U.S. tax residency.

When the Substantial Presence Test Creates “Dual Residency”

It’s common for New Zealanders and Australians who spend extended periods in the U.S. to trigger the SPT while remaining residents of NZ or AU under their home country’s law. This creates dual residency—tax residency in both the U.S. and your home country.

To resolve this, the U.S. has tax treaties with both New Zealand and Australia that include residence tie-breaker rules.

Residence Tie-Breaker Rules in the U.S.–New Zealand Tax Treaty

Under Article 4 of the U.S.–New Zealand tax treaty, if you are a resident of both countries, your residence is determined as follows:

1. Permanent home – where you maintain a permanent home.
2. Centre of vital interests – where your family, work, and economic ties are strongest.
3. Habitual abode – where you spend the majority of your time.
4. Citizenship – if the above remain unresolved.
5. Competent authority agreement – final resolution by U.S. and NZ tax authorities.

This step-by-step test helps avoid double taxation when the SPT overlaps with New Zealand tax residency.

Residence Tie-Breaker Rules in the U.S.–Australia Tax Treaty

The U.S.–Australia tax treaty (Article 4) has a slightly different tie-breaker structure:

1. Permanent home – priority goes to the country where you have a permanent dwelling.
2. Habitual abode – if homes exist in both countries or neither, residence goes to where you habitually live.
3. Closer personal and economic relations – if still unresolved, competent authorities determine where your primary ties lie.

Unlike the NZ treaty, the AU treaty does not include citizenship as a deciding factor.

Key Compliance Requirements

• Treaty claims require disclosure. If you invoke the residence tie-breaker rules, you must file Form 8833 with your U.S. return. This formally declares that you are a treaty resident of NZ or AU, not the U.S.
• U.S. citizens cannot use treaty tie-breakers. Both the NZ and AU treaties contain a saving clause allowing the U.S. to tax its citizens as if the treaty did not exist. These rules mainly help green card holders and non-citizens.
• Closer connection exception vs. treaty tie-breaker. The closer connection exception (Form 8840) is available only if you spend less than 183 days in the U.S. in the current year. Once you exceed 183 days, you generally need to rely on treaty tie-breakers (Form 8833).

Why Residence Tie-Breaker Rules Matter

For expatriates, temporary workers, and frequent travelers between the U.S., New Zealand, and Australia, the interaction between the substantial presence test and treaty residence rules is critical.

• Without applying a tie-breaker, you could be considered a U.S. resident and taxed on worldwide income.
• By correctly applying the treaty rules, you may limit U.S. taxation to U.S.-source income only.
• Proper filing (Form 8840 or Form 8833) ensures compliance and avoids IRS penalties.

Final Thoughts

The residence tie-breaker rules in the U.S.–New Zealand and U.S.–Australia tax treaties provide essential relief for individuals who meet the substantial presence test but maintain stronger ties abroad. Correctly applying these provisions ensures you are not unfairly subjected to double taxation and that your U.S. filings remain compliant.

For many expats, understanding the difference between the SPT, the closer connection exception, and treaty tie-breakers can mean thousands of dollars in tax savings and peace of mind.