Mega Backdoor Roth Conversions for US Expats

The mega backdoor Roth is a strategy where an employee makes after-tax 401(k) contributions above the normal pre-tax and Roth contribution limits and then rolls those contributions into a Roth IRA or converts them in-plan to a Roth 401(k). For this to work, your employer's 401(k) plan must allow after-tax contributions and either in-service distributions or in-plan conversions, and not all plans permit this. If you're working for a US employer from abroad and are still eligible to contribute to their 401(k), the mega backdoor Roth can work the same way it would for a US-based employee. The after-tax contributions themselves are not taxable since you've already paid tax on that money; only the earnings on those contributions are taxable when converted, and in practice those earnings are minimal if you convert quickly after contributing. This strategy is particularly valuable for high earners who cannot make direct Roth IRA contributions due to income limits, including many expats in lower-tax countries who still have significant US-dollar income.