Superannuation vs 401k: Key differences every US expat in Australia must know in 2026
Quick answer box
- Mandatory vs voluntary. Superannuation is a mandatory employer contribution under Australian law; a 401(k) is a voluntary employee election under the US Internal Revenue Code.
- US tax treatment. 401(k) deferrals reduce your US taxable income in the year of contribution. Australian super contributions generally do not – the IRS treats them as current taxable income unless you make a treaty election.
- Reporting burden. A 401(k) requires no special international forms. Australian super can trigger Form 3520, Form 3520-A, and Form 8621, depending on your fund type and balance – some standard super funds qualify for filing relief under IRS rules.
Both are employer-linked retirement vehicles, but that is where the similarities end. The IRS treats the two very differently, and confusing the two is one of the most common – and costly – mistakes US expats in Australia make.
Superannuation and a 401(k) are not equivalent retirement plans under US tax law, and contributions to an Australian super fund do not receive the same pre-tax treatment as 401(k) deferrals for US taxpayers.
What is a 401(k)? How the US retirement system works
A 401(k) is a voluntary, employer-sponsored defined-contribution plan governed by IRC Section 401(k). You fund it through pre-tax or Roth after-tax employee deferrals, and your employer may add a matching contribution on top.
The account grows tax-deferred, meaning you owe no US federal income tax on investment gains until you take a distribution – typically in retirement.
For tax year 2025, the key contribution limits are:
- Employee elective deferral: $23,500 (2025)
- Catch-up contribution (ages 50–59 and 64+): $7,500 (2025)
- Enhanced catch-up (ages 60–63, SECURE 2.0 Act): $11,250 (2025)
- Total combined limit (Section 415(c)): $70,000 (2025), or $77,500 (2025) with standard catch-up
Traditional 401(k) contributions come out of your paycheck before federal income tax is calculated, which directly reduces your US taxable income for the year.
Penalty-free withdrawals begin at age 59½, and required minimum distributions (RMDs) start at age 73 for those born between 1951 and 1959, and at age 75 for those born in 1960 or later, under the SECURE 2.0 Act.
A 401(k) reduces US taxable income in the year of contribution, a benefit that does not automatically extend to Australian superannuation for US taxpayers.
That single difference – explicit tax deferral under the IRC versus no automatic US recognition – drives most of the compliance complexity covered below.
The IRS has clear rules for 401(k) plans. It has no equivalent framework for super.
Types of 401(k) plans: traditional, Roth, and Solo
There are three main 401(k) structures, each with different tax treatment on contributions and withdrawals.
- Traditional 401(k) – pre-tax contributions reduce your gross income now; withdrawals in retirement are taxed as ordinary income.
- Roth 401(k) – after-tax contributions provide no upfront deduction, but qualified withdrawals – including earnings – are federal income tax-free.
- Solo 401(k) – designed for self-employed individuals with no full-time employees other than a spouse. You can make both employee deferrals and employer profit-sharing contributions.
What is superannuation? How Australia’s retirement system works
Superannuation – “super” in everyday Australian English – is Australia’s mandatory employer-funded retirement system. Under the Superannuation Guarantee, every Australian employer must contribute a percentage of each employee’s ordinary time earnings into a complying super fund.
As of 1 July 2025, that rate is 12% for the 2025–26 financial year.
The money is locked away. You generally cannot access your super until you reach preservation age – currently 60 for anyone born after 30 June 1964 – and meet a condition of release, such as retiring from the workforce.
There are limited exceptions for severe financial hardship, terminal illness, or permanently leaving Australia as a temporary visa holder.
Unlike a 401(k), superannuation contributions are mandatory for Australian employers and are not elected by the employee, making the two systems structurally different from the outset.
For US tax purposes, the critical issue is that the IRS does not recognize Australian super as a qualified retirement plan.
That means employer contributions to your super fund are generally included in your US gross income in the year they are made – even though you cannot touch the money for decades.
Types of superannuation funds: industry, retail, SMSF, and more
The fund type determines how the IRS classifies your super – and which forms you need to file.
- Industry funds – non-profit funds run for the benefit of members, often tied to a specific sector such as healthcare or construction.
- Retail funds – operated by financial institutions for profit, offering a broader range of investment options.
- Self-managed super funds (SMSFs) – regulated by the ATO, with a maximum of six members who are also trustees. SMSFs are particularly complex for US persons because they may trigger additional IRS reporting as foreign grantor trusts.
- Corporate funds – employer-sponsored funds set up for a single company’s employees. These are less common and are typically closed to new members outside the sponsoring company.
Most US expats in Australia will have their super in an industry or retail fund chosen by their employer. The fund type matters for US tax purposes because it determines the IRS classification – and therefore the reporting forms you need to file.
Is 401k the same as superannuation? A direct comparison
No. Comparing 401k vs superannuation reveals that the two systems share a surface-level resemblance – both are employer-linked, both hold retirement savings, both offer some form of tax preference in their home country.
But the differences are fundamental, especially for anyone who files a US tax return.
The single most important difference for US taxpayers is that 401(k) contributions are explicitly excluded from US gross income under the IRC, while Australian super contributions made by an employer are generally taxable to a US person in the year contributed.
| Feature | 401(k) | Australian superannuation |
|---|---|---|
| Mandatory or voluntary | Voluntary employee election | Mandatory employer contribution |
| Who contributes | Employee, with optional employer match | Employer (12% SG rate for 2025–26); voluntary employee contributions also allowed |
| Contribution limits (2025) | $23,500 employee deferral; $70,000 total | Employer SG contributions apply up to the maximum contribution base (AUD 62,500 per quarter for 2025–26); concessional contribution cap is AUD 30,000 |
| Tax treatment in home country | Pre-tax (traditional) or after-tax (Roth) | 15% contributions tax within the fund |
| US tax treatment | Excluded from US gross income under IRC | Generally included in US gross income unless treaty election claimed |
| Access age | 59½ (penalty-free) | Preservation age 60 + condition of release |
| Portability | Rollover to IRA or new employer 401(k) | No rollover to US plans; DASP for departing temporary residents |
| IRS classification | Qualified retirement plan | Foreign trust (grantor or non-grantor, depending on fund type) |
How the IRS classifies Australian superannuation
The IRS does not recognize Australian superannuation as a qualified retirement plan under the Internal Revenue Code. Instead, it generally classifies super as a foreign trust.
Whether the trust is a foreign grantor trust or a non-grantor trust depends on the fund type and the US person’s level of control.
For most accumulation-phase industry and retail funds, employer contributions are not shielded from US income tax the way 401(k) deferrals are. They are generally includible in the US person’s gross income in the year contributed.
This classification generally triggers two separate reporting tracks, though relief is available in some cases:
- Foreign trust reporting: Form 3520 and Form 3520-A, unless the fund qualifies for the Revenue Procedure 2020-17 exemption for certain tax-favored foreign retirement trusts (most SMSFs do not qualify).
- Penalties for non-filing: The greater of $10,000 or 35% of the gross reportable amount for unreported transfers or distributions, and the greater of $10,000 or 5% of the gross value of trust assets for unreported ownership.
- PFIC reporting: The investments held inside super may be classified as passive foreign investment companies, generally requiring a separate Form 8621 for each PFIC holding, unless a de minimis exception applies (combined PFIC holdings of $25,000 or less, $50,000 if married filing jointly, with no excess distributions or dispositions).
Failing to report an Australian super fund to the IRS can result in significant penalties, including those associated with Form 3520 and FBAR obligations.
PFIC rules and Australian superannuation: What US expats must report
The PFIC rules are where Australian super becomes genuinely complex for US taxpayers. Here is what you need to know.
- What is a PFIC? A passive foreign investment company is any foreign corporation where 75% or more of gross income is passive, or 50% or more of assets produce passive income. Most managed funds inside Australian super meet this definition.
- Why super funds typically contain PFICs. Industry and retail super funds invest in pooled trusts, managed funds, and index funds domiciled outside the US. Each of these underlying holdings is likely a separate PFIC.
- Three PFIC tax regimes. You can make a QEF election to include your pro rata share of the PFIC’s ordinary earnings and net capital gain annually, or a mark-to-market election to recognize unrealized gains each year. Without either election, the default excess distribution regime under IRC Section 1291 applies, and it is the most punitive of the three.
- Form 8621 filing requirement. Each PFIC holding generally requires a separate Form 8621, filed with your annual US return, though a de minimis exception can apply when combined PFIC holdings are $25,000 or less ($50,000 if married filing jointly), and there are no excess distributions or dispositions.
Read more on PFIC rules – including how QEF and mark-to-market elections work, the excess distribution tax calculation, and what happens when you miss a Form 8621.
Based on a common TFX client scenario, a US person holding a diversified industry super fund with 15 underlying managed funds may need to file 15 separate Form 8621s, unless the combined year-end value of those holdings falls under the $25,000 ($50,000 married filing jointly) de minimis exception.
This is exactly the kind of filing where professional preparation is not optional – it is essential.
US-Australia tax treaty and superannuation: Does it help?
The US-Australia Income Tax Treaty contains provisions that may offer some relief – but the operative word is “may.”
Article 18 addresses pensions and retirement benefits. Under certain conditions, some practitioners argue it may allow a US citizen or resident to defer US tax on earnings accruing inside a complying Australian super fund, but the treaty does not specifically mention superannuation, and the IRS has issued no formal guidance confirming this position.
This relief is not automatic. You must affirmatively claim the treaty benefit by filing Form 8833 with your US return.
The treaty’s saving clause – a standard provision that preserves each country’s right to tax its own citizens – limits the scope of the deferral.
The US retains the right to tax its citizens on worldwide income, and the treaty benefits available to Australian residents who are not US citizens may not be available to you in the same way.
The US-Australia tax treaty offers potential tax deferral on super fund earnings, but US citizens must affirmatively claim treaty benefits and understand the interaction with the saving clause.
The treaty election may defer US tax on investment earnings inside your super fund until distribution. It does not eliminate the tax. And it does not change the classification of super as a foreign trust or remove the PFIC reporting obligations.
Social Security totalization agreement: US and Australia
The US and Australia have a totalization agreement that addresses a different problem: double Social Security taxation. If you split your career between the two countries, this agreement prevents you from paying into both systems simultaneously on the same income.
It also lets you combine work credits from both countries to qualify for benefits.
For example, combining 7 years of US credits with 5 years of Australian credits meets the 10-year threshold for US Social Security retirement benefits.
Key points:
- US expats working in Australia for an Australian employer are generally exempt from US Social Security tax on those wages under the totalization agreement.
- The agreement covers Social Security contributions only – not income tax treatment. It does not make superannuation equivalent to a 401(k) for US income tax purposes.
Can you transfer superannuation to a 401k or IRA?
There is no mechanism under US or Australian law to directly roll over or transfer superannuation to a 401(k) or IRA. The two systems are legally incompatible for rollover purposes.
The IRS requires that rollovers come from a “qualified plan” or an “eligible retirement plan” as defined in the IRC, and Australian super does not meet either definition.
You cannot roll over Australian superannuation into a US 401(k) or IRA; any withdrawal from super paid to a US person is a taxable distribution under both Australian and US tax rules.
If you want to move money out of super, your options depend on your residency status:
- Temporary visa holders who permanently leave Australia may claim a Departing Australia Superannuation Payment.
- Australian citizens and permanent residents are not eligible for DASP. They must wait until preservation age and meet a condition of release – regardless of where they live.
DASP withholding rates and US tax treatment
A DASP is subject to Australian withholding tax at these rates:
- Tax-free component: 0%
- Taxed element: 35%
- Untaxed element: 45%
- Working holiday makers: 65% on both taxed and untaxed elements
The payment must also be reported as income on your US return – it does not qualify for rollover treatment.
You may be able to claim a foreign tax credit for the Australian withholding tax paid, which reduces the double-tax impact but does not eliminate it entirely.
What happens to your 401(k) when you move to Australia?
Your 401(k) does not disappear when you relocate, but the rules around contributions, distributions, and reporting shift in ways that matter.
- Your 401(k) stays in the US. The account remains with your US plan administrator and continues to grow tax-deferred under US rules. There is no requirement to close, cash out, or transfer the account when you move abroad.
- You generally cannot contribute from Australian income. 401(k) contributions must come from compensation earned through an employer that sponsors the plan. If you leave your US employer and work for an Australian company, you will not have a 401(k) to contribute to – but the existing balance keeps compounding.
- Distributions may be subject to Australian tax. If you take a distribution while you are an Australian tax resident, Australia may tax that income under its domestic rules. The US-Australia tax treaty may provide relief from double taxation.
- No special international reporting is required for the 401(k) itself. A US domestic retirement account is not a foreign financial account, so it does not appear on your FBAR or Form 8938. However, distributions are still reportable on your US return.
Your 401(k) does not need to be closed or transferred when you move to Australia. Review your investment options and beneficiary designations before departing.
Read more on moving to Australia – including visa-linked tax residency rules, pre-departure filing steps, and how superannuation enrollment works from day one.
What happens to your superannuation when you leave Australia?
Former temporary residents who permanently leave Australia may be eligible to claim their superannuation balance as a Departing Australia Superannuation Payment. The DASP process is managed through the ATO.
For a US person, a DASP does not end the tax story. The payment is treated as a foreign pension distribution and included in US gross income. You report it on your US return in the year received, and you may claim a foreign tax credit for the Australian withholding tax paid.
Claiming a DASP does not eliminate US tax liability – the payment is treated as a foreign pension distribution and included in US gross income, with a potential foreign tax credit for Australian withholding tax paid.
Australian citizens and permanent residents are not eligible for DASP. Your super stays in Australia until you reach preservation age and meet a condition of release – regardless of where you live.
FBAR and FATCA reporting for Australian superannuation
Australian superannuation is a reportable foreign financial account, and most US persons with super must file two separate information returns annually:
- FBAR (FinCEN Form 114). If the aggregate value of all your foreign financial accounts – including your super balance – exceeds $10,000 on any day during the year, you must file an FBAR. The filing deadline is April 15, with an automatic extension to October 15.
- Form 8938 (FATCA). If your foreign financial assets exceed the applicable threshold – $200,000 at year-end or $300,000 at any point during the year for expats filing single – you must attach Form 8938 to your US return. Thresholds are higher for married filing jointly.
Your super balance counts toward the $10,000 FBAR threshold even though you cannot access it.
Based on a common TFX client scenario, a US person with a $150,000 Australian super balance who fails to file an FBAR faces a non-willful penalty of up to $16,536 (for assessments on or after January 17, 2025) per unfiled report, not per account. Professional filing is far less costly than the penalty.
Australian superannuation is a reportable foreign financial account for FBAR purposes, and most US persons with super must file FinCEN Form 114 annually.
Foreign Earned Income Exclusion and retirement contributions
US expats who claim the Foreign Earned Income Exclusion on Form 2555 exclude qualifying foreign earned income from US gross income. For tax year 2025, the maximum exclusion is $130,000 (2025).
The FEIE reduces the earned income base available for IRA contributions. If you exclude all of your foreign earned income, you may have no earned income remaining to support a traditional or Roth IRA contribution.
The IRS requires that IRA contributions come from “compensation” – and income excluded under the FEIE does not count.
Employer superannuation contributions do not help here either. They are not “earned income” for FEIE purposes, and they are not “compensation” for IRA contribution purposes.
Here is how the gap works in practice: if your Australian salary is $120,000 and the FEIE eliminates all of it from your US taxable income, which is possible any time your foreign earned income falls below the $130,000 (2025) ceiling, your remaining earned income for IRA purposes is zero, even though your employer is contributing 12% of your salary into super.
Claiming the FEIE can inadvertently eliminate your ability to make IRA contributions for that tax year.
Which is better for US expats: superannuation or 401(k)?
There is no universally better option. The right strategy depends on your residency timeline, citizenship status, and whether you can claim treaty benefits to defer US tax on super earnings.
| Scenario | Best approach |
|---|---|
| US expat in Australia long-term | Super is unavoidable since your employer must contribute. Focus on the treaty deferral election and keep PFIC reporting current. |
| US expat in Australia short-term | Minimize voluntary super contributions. If you still have a US employer offering a 401(k), maximize that instead. |
| Australian in the US | Contribute to a 401(k) through your US employer. Manage your existing super reporting obligations from the US side. |
| Dual citizen | Both systems apply. You will need specialist planning to avoid double taxation and missed filings across both countries. |
Cross-border retirement planning strategy for US-Australia expats
A structured approach to cross-border retirement planning helps you avoid the most common and costly errors. Here are five steps:
- Determine your long-term residency intention. Before making any irreversible retirement decisions – cashing out super, rolling over a 401(k), making voluntary contributions – decide whether you plan to retire in the US, Australia, or somewhere else entirely. That answer drives everything.
- Assess whether the US-Australia treaty deferral election is available and beneficial. Not every super fund qualifies, and the benefit depends on your specific situation. File Form 8833 if you are claiming treaty benefits.
- Identify all PFIC holdings inside your super fund. Review the fund’s investment menu and determine which underlying holdings are PFICs. Evaluate whether a QEF election, mark-to-market election, or the default excess distribution regime produces the best outcome.
- Ensure all information returns are current. That means FBAR, Form 8938, and, where applicable, Form 3520, Form 3520-A, and Form 8621 (some standard super funds and smaller PFIC holdings may qualify for filing relief). If you are behind on any of these, the streamlined filing procedures may offer a path to catch up before penalties compound.
- Model the after-tax retirement income from both systems. Work with a cross-border tax specialist to project what your super and 401(k) will actually deliver after US and Australian taxes, treaty elections, and foreign tax credits are factored in.
Read more on expat financial planning – covering investment structuring, currency risk, and how to coordinate US and foreign retirement accounts over a multi-decade horizon.
Common mistakes US expats make with superannuation and 401(k) accounts
These are the errors TFX sees most often from US-Australia clients. Each one can trigger penalties that far exceed the tax savings the expat was trying to achieve.
Mistakes on the superannuation side
Each of these errors can result in penalties that exceed the underlying tax liability.
- Assuming super is tax-deferred for US purposes without a treaty election. It is not. Without an affirmative election on Form 8833, employer contributions and fund earnings are generally includible in US gross income.
- Assuming Form 3520 or Form 3520-A is required without checking for the Revenue Procedure 2020-17 exemption. Many standard industry and retail super funds qualify for relief from these filings; SMSFs generally do not. Where the exemption doesn’t apply, and a required form is missed, the penalty is the greater of $10,000 or 35% of the gross reportable amount for an unreported transfer to or distribution from the trust, or the greater of $10,000 or 5% of the trust’s gross value for unreported ownership.
- Not filing Form 8621 for PFIC holdings inside super. Each underlying managed fund likely qualifies as a separate PFIC, and each one generally needs its own Form 8621, unless your combined PFIC holdings are $25,000 or less ($50,000 or less married filing jointly) with no excess distributions or dispositions during the year.
- Omitting super from FBAR and Form 8938. Your super balance counts toward the $10,000 FBAR threshold even though you have no access to the money.
- Withdrawing super early without modeling the combined tax cost. A DASP triggers Australian withholding tax up to 45% for most temporary residents, and up to 65% if you ever held a working holiday maker visa (subclass 417 or 462), plus US income tax on the full amount. The foreign tax credit offsets some of the double hit, but the total burden can be substantial.
Mistakes on the 401(k) side
The 401(k) itself is simpler, but the FEIE interaction catches many expats off guard.
Contributing to an IRA in a year when the FEIE eliminates all earned income. You may have zero eligible compensation for IRA contribution purposes, and the IRS treats excess contributions as a 6% penalty per year until corrected.
Frequently asked questions
No. A 401(k) is a voluntary US plan with explicit tax deferral under the IRC. Superannuation is a mandatory Australian system that the IRS classifies as a foreign trust, with no automatic US tax deferral. The reporting obligations are vastly different.
No. There is no rollover mechanism between Australian super and US retirement accounts. The IRS requires rollovers to come from qualified plans under the IRC, and Australian super does not qualify. Any withdrawal from super is treated as a taxable distribution, not a rollover.
Generally, yes, though you may not need to file Form 3520 and Form 3520-A if your fund qualifies for the exemption under Revenue Procedure 2020-17. You may also need to file Form 8621 for PFIC holdings, subject to the $25,000 ($50,000 married filing jointly) de minimis exception. You also report the account on an FBAR and Form 8938 if you meet the filing thresholds. Employer contributions may also be includible in your US gross income in the year contributed.
In most cases, yes. The underlying managed funds inside a typical industry or retail super fund are likely classified as PFICs under IRC Section 1297.
Each PFIC holding generally requires a separate Form 8621, unless your combined PFIC holdings are $25,000 or less ($50,000 or less married filing jointly) with no excess distributions or dispositions during the year. Without a QEF or mark-to-market election, the default tax regime is the most punitive of the three available options.
For anyone born after 30 June 1964, the preservation age is 60. Earlier birth cohorts have lower preservation ages ranging from 55 to 59. You must also meet a condition of release – such as retirement – to access your super, even after reaching preservation age.
Partially, and only if you claim it. Article 18 may allow you to defer US tax on super fund earnings, but you must make an affirmative election by filing Form 8833 with your US return.
The treaty does not eliminate the foreign trust or PFIC reporting requirements.
The typical package often includes Form 3520, Form 3520-A, and Form 8621 for each PFIC holding, though some standard super funds and smaller PFIC holdings may qualify for filing exceptions. Add FBAR if aggregate foreign account balances exceed $10,000. Include Form 8938 if you exceed the FATCA thresholds. File Form 8833 if claiming treaty benefits.
Generally, yes. Accumulation-phase super funds are treated as foreign financial accounts for FBAR purposes. Pension-phase accounts may have a different analysis depending on the fund structure.
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