The bottom line

You leave the US with a 401(k). You have four options: leave it where it is, roll it to a US-based IRA, take a cash distribution, or — rarely available — transfer to a foreign retirement plan. For most expats, rolling to an IRA before you board the plane is the right move: it preserves tax deferral, removes employer-plan fees, expands investment choice, and keeps you out of the cash-distribution trap. Foreign countries treat US retirement accounts unevenly — some respect tax deferral (UK, Canada via treaty), others tax annual gains as if you held the underlying directly (Australia, Japan in some cases). Always check the bilateral treaty before you assume your 401(k) stays untaxed in your new country.

The four options on the table

1. Leave the 401(k) with your former employer

Allowed in most plans if your balance is over $7,000 (a 2024 SECURE 2.0 change raised this from $5,000). Below that threshold the plan can force you out into a default IRA — they'll tell you within 60 days.

Pros: zero action required, tax deferral preserved, creditor protection under ERISA is strong (better than IRA in most states).

Cons: limited investment menu (whatever your employer chose), often higher expense ratios than a self-directed IRA, harder to manage from overseas if the plan administrator's website is geo-blocked, customer service is US-time.

2. Roll the 401(k) to a US-based IRA

This is the default recommendation for most expats. A direct trustee-to-trustee rollover is a non-taxable event under IRC §402(c). The funds move from the 401(k) custodian (Fidelity, Empower, Vanguard, Schwab) to your IRA custodian without ever touching your hands.

Why it's usually right:

  • Open the entire investment universe (any ETF, mutual fund, individual stock).
  • Lower expense ratios than most 401(k) lineups.
  • One account to manage forever, no employer-plan idiosyncrasies.
  • Easier for a financial planner to manage on your behalf.
  • US-resident addresses are easier than foreign ones; do this before you change your address abroad if your IRA custodian is restrictive about non-US-resident clients (some are — Fidelity and Vanguard both have policies; Charles Schwab International is more flexible).

Watch out for:

  • Aggregation rule for IRAs — once the money is in an IRA, the pro-rata rule for backdoor Roth conversions starts applying across all your traditional IRAs. If you have a non-deductible IRA you want to convert, do that conversion before rolling the 401(k).
  • Loss of NUA (Net Unrealized Appreciation) treatment for company stock — if you have employer stock in your 401(k) with significant unrealized gains, rolling to an IRA destroys the NUA election. Take the company stock as an in-kind distribution to a taxable brokerage first, then roll the rest. Only do this with professional help.

3. Take a cash distribution

Almost always wrong if you're under 59½. A cash distribution triggers:

  • Ordinary income tax on the full amount (federal + state of last residence).
  • A 10% early-withdrawal penalty under IRC §72(t) unless an exception applies.
  • Mandatory 20% federal withholding at distribution (which is rarely enough — see the RSU guide for the same trap).
  • Potentially a higher marginal rate in your final US-resident year because the distribution stacks on your other income.

Combined hit: a $200,000 401(k) cashed out by a 35-year-old in the 32% bracket could net ~$112,000 after federal tax + 10% penalty + state tax. The remaining $88,000 lost in a single transaction is the cost of avoiding the rollover paperwork.

The only realistic case for cashing out: very small balances (under ~$10k) where the future tax-deferral compounding doesn't justify the administrative complexity, and the recipient is in a low-bracket year.

4. Transfer to a foreign pension

Only available between the US and a small set of countries — and even there, only between specific plan types. The most prominent example: Roth 401(k) to a UK Self-Invested Personal Pension (SIPP) is not generally allowed; the UK doesn't recognize US Roth as a tax-free wrapper for transfer-in purposes.

The closest workable structures: lump-sum distribution + new contribution to a foreign pension (pays full US tax on the way out), or treaty-based "qualifying recognised overseas pension scheme" (QROPS) transfers in some cases (mostly for UK departures from US, not the other way around).

For most expats, this option is unavailable in practice. Don't spend energy on it.

How your new country treats a US 401(k) / IRA

This is the part most people get wrong. Each country decides whether to honor US tax deferral on accounts held by its residents.

  • UK: The US-UK treaty Article 17(1) protects tax deferral inside both 401(k)s and IRAs while the holder is a UK resident. Distributions are taxed by the UK at the time of withdrawal (with an exception for Roth IRAs, where the treaty is less clean — get advice).
  • Canada: US-Canada treaty Article XVIII generally honors deferral; Canadian residents can take an annual election to defer. Canadian withholding tax may apply on distributions.
  • Australia: Australia does not defer tax on growth inside US retirement accounts under most treaty interpretations — you may owe Australian tax annually on accrued gains as if held directly. This is the harshest expat-401(k) situation among major destinations.
  • Germany: Treaty offers some protection; the German tax authority's position is conservative. Get advice before assuming deferral.
  • Singapore / UAE / Hong Kong: No personal income tax on most income — so the question is moot for residents.
  • Japan: Tax treatment of US retirement-plan growth has historically been ambiguous; recent guidance has tightened. Distributions taxed by Japan but there can be foreign-tax-credit relief.

The general rule: treaty Article 17 (or its country-specific equivalent) is the binding text. Read it. Most countries with active US treaties allow deferral; outliers exist.

The non-resident distribution trap

When you eventually take a distribution after leaving the US:

  • Your 401(k)/IRA custodian withholds 30% federal tax by default for nonresident aliens.
  • A treaty may reduce this — file Form W-8BEN with the custodian to claim the treaty rate (often 15% for periodic pensions).
  • Roth IRA distributions: qualified distributions are tax-free under US law and many treaties also exempt them from foreign tax. Some treaties don't — always check.
  • File Form 1040-NR for the year of the distribution to reconcile withholding against actual liability.

If you forget the W-8BEN, the 30% goes to the IRS up front and you have to claim a refund on the 1040-NR — a 12+ month wait.

Worked example

You're 35, leaving the US for the UK, with a $250,000 401(k) at Empower. Plan: rollover to Schwab IRA, then move to UK.

Steps:

  1. Open a Schwab IRA while still US-resident. Some custodians lock you out if you're already abroad.
  2. Initiate a direct rollover from Empower to Schwab. The check or wire is made payable to "Schwab as custodian for [your name] IRA". Don't deposit it into your bank. (This is a non-taxable event, but the 60-day window for indirect rollover is a trap — direct only.)
  3. Confirm full rollover amount lands in the Schwab IRA, no withholding.
  4. Update your address with Schwab once you're in the UK.
  5. File W-8BEN with Schwab so future distributions are coded for nonresident-alien treatment.
  6. Once UK-resident, declare the IRA on UK tax return as required, claim Article 17 deferral on growth.
  7. At retirement (age 59½+), distributions: Schwab withholds 15% under treaty, you pay UK tax with a foreign-tax credit for the US 15%.

Total tax cost of the rollover: $0. If you'd cashed out instead at age 35:

  • US federal tax (32%): $80,000
  • 10% early-withdrawal penalty: $25,000
  • State tax (5% from last state of residence): $12,500
  • Net to you: $132,500 out of $250,000.

Compounding cost: that $132,500 at 7% real over 25 years until age 60 grows to ~$719,000. The intact $250,000 IRA at the same rate grows to ~$1,357,000. Cost of cashing out instead of rolling: ~$638,000.

Practical checklist before you leave the US

  • ✅ Confirm 401(k) balance and whether plan supports direct rollover.
  • ✅ Open IRA at a custodian that accepts non-US-resident clients (Charles Schwab International, Interactive Brokers).
  • ✅ Initiate direct trustee-to-trustee rollover before you change your address.
  • ✅ Update beneficiaries on the new IRA (bring foreign-resident spouses with passport info).
  • ✅ File W-8BEN with the IRA custodian once you're a non-US-resident for tax purposes.
  • ✅ Read the bilateral US treaty Article 17 (pensions) for your destination country.
  • ✅ Engage a cross-border CPA in your destination country for the first year — they'll catch reporting requirements (Form 8938 / FBAR if you keep US accounts, foreign-pension reporting in the new country, etc.).
  • ❌ Don't cash out unless you're certain.
  • ❌ Don't ignore the W-8BEN; the default 30% withholding is a forced loan to the IRS.
  • ❌ Don't assume the destination country honors Roth IRA tax-free status without checking the treaty.

The 401(k) you leave behind is not abandoned money — it's a continuing relationship with US tax law. Manage it actively. Most expats who get this right at departure save themselves five-figure mistakes a decade later.