US 401(k) Tax in Australia: Withdrawals, Rollovers and Treaty Issues

Is a US 401(k) withdrawal taxable in Australia?

Usually, an Australian tax resident cannot assume that a 401(k), traditional IRA or Roth IRA will receive the same tax treatment in Australia that it receives in the United States. The result depends on the legal terms of the particular plan, the member’s Australian and US status, the character of the payment, contributions and earnings records, foreign exchange movements, and the Australia–US tax treaty.

A withdrawal should therefore be modelled before funds are moved. The Australian tax outcome may differ materially depending on whether the arrangement qualifies as a foreign superannuation fund or is instead treated under Australia’s foreign-trust rules.

The first question: is the plan a foreign superannuation fund?

Australian law does not classify an arrangement solely by its US label. A 401(k) may fail the Australian concept of a superannuation fund where the plan permits benefits to be accessed for purposes extending beyond retirement, death, disability or another permitted retirement purpose.

The analysis is plan-specific. The plan deed, summary plan description, hardship-withdrawal rules and the member’s actual rights must be reviewed. An edited ATO private-advice record issued in January 2024 concluded, on its particular facts, that a 401(k) was not a foreign superannuation fund. Edited private advice is not precedent and cannot be relied on by another taxpayer, but it demonstrates the classification risk.

What happens if the 401(k) is not foreign superannuation?

Where the plan is not a foreign superannuation fund, the special foreign-super lump-sum rules in Division 305 may not apply. The Australian analysis may instead involve the foreign-trust distribution rules, including section 99B of the Income Tax Assessment Act 1936 and potentially the interest-charge rules in section 102AAM.

It is unsafe to state as a universal rule that Australia taxes only the investment growth above contributions. Section 99B contains exclusions, including for amounts representing corpus, but the result depends on the legal character of the payment and the taxpayer’s ability to trace and substantiate contributions, prior distributions and accumulated income. Inadequate records can materially worsen the position.

Key records commonly include contribution statements separating pre-tax, employer and after-tax amounts; account values when Australian tax residence commenced; complete rollover and distribution history; plan documents and hardship-access rules; US federal and state tax withheld or paid; and exchange rates for each relevant transaction and valuation date.

What if the arrangement does qualify as foreign superannuation?

If the arrangement is a foreign superannuation fund, Division 305 may apply to a lump sum received after the taxpayer becomes an Australian resident. Broadly, the applicable fund earnings component may be assessable, subject to the detailed statutory calculation and possible elections where an amount is transferred to a complying Australian superannuation fund.

The six-month rules, residence dates, transfer mechanics and contribution caps require separate testing. A rollover between two US arrangements is not automatically a basis reset for Australian tax purposes.

How does the Australia–US tax treaty affect a withdrawal?

Article 18 of the Australia–US treaty generally allocates pensions and similar remuneration paid to an Australian resident to Australia. The US Treasury technical explanation indicates that the pension article can extend to lump sums and IRAs.

However, the treaty’s saving clause generally preserves the United States’ right to tax its citizens and residents as though the treaty had not entered into force. Accordingly, a US citizen or green-card holder should not assume that Australian residence prevents US tax on a 401(k) or IRA distribution.

For a person who is neither a US citizen nor a US tax resident, treaty relief and US withholding may be relevant, but the correct result depends on residence, plan type, payment character and documentation. Form W-8BEN is generally a form for a non-US person; it is not the standard form for a US citizen or other US person.

US federal and state considerations

Traditional 401(k) and IRA distributions are commonly taxable in the United States to the extent they do not represent after-tax basis. A distribution before age 59½ may also attract the additional 10% US tax unless an exception applies.

Roth arrangements require separate analysis. A distribution that is qualified and tax-free in the United States is not automatically exempt in Australia. State tax must also be checked because state residence and domicile rules do not always follow the federal treaty outcome.

Can foreign tax offsets prevent double taxation?

An Australian foreign income tax offset may be available where foreign income tax is paid in respect of an amount included in Australian assessable income. The offset is not automatically equal to all US tax or withholding. Timing, source, treaty allocation, the Australian amount included and the foreign-income-tax-offset limit can affect the result.

For US citizens, the double-tax analysis may also require consideration of whether Australia or the United States provides the effective credit under the treaty and domestic rules for the particular item.

Planning before a withdrawal

Planning commonly requires confirming Australian and US tax residence and citizenship or green-card status; classifying each plan under Australian law; reconstructing corpus, contributions, earnings and exchange-rate records; comparing a lump sum with staged distributions; checking US early-distribution and state-tax exposure; modelling Australian section 99B, Division 305 and foreign-tax-offset outcomes; and separately considering Australian superannuation contributions within the applicable caps.

The lowest-tax option cannot be identified reliably from the current account balance alone.

Frequently asked questions

Does rolling a 401(k) into an IRA reset the Australian tax cost base?

Not as a general rule. A US rollover may be tax-deferred in the United States, but its Australian consequences depend on the legal transaction, the classification of both arrangements and the applicable Australian provisions.

Is only the growth since moving to Australia taxable?

Not necessarily. That may resemble the outcome under some foreign-super calculations, but a non-super foreign-trust analysis can operate differently. Contributions and corpus exclusions require evidence and tracing.

Does the treaty stop US tax once I live in Australia?

Not generally for a US citizen or green-card holder because of the saving clause. Non-US persons require a separate treaty and withholding analysis.

Is a Roth IRA tax-free in Australia?

US tax-free status does not itself determine the Australian result. The Roth arrangement and distribution must be classified under Australian law.

Primary sources

ATO edited private advice 1052206521277; Income Tax Assessment Act 1936 sections 99B and 102AAM; Income Tax Assessment Act 1997 Division 305 and Division 770; Australia–US tax treaty and US Treasury technical explanation; IRS Topics 410 and 424.

Before acting

A 401(k), IRA or Roth IRA withdrawal is a cross-border transaction, not merely a US retirement decision. Extax Advisory can prepare a transaction-specific US–Australia retirement-plan tax review before a rollover or withdrawal is implemented.

This article is general information only. It does not constitute tax or legal advice. The legislation, treaty, plan documents and individual facts must be reviewed before reliance.