Solo 401(k) vs SEP IRA for Self-Employed Americans in Hong Kong: Retirement Plan Comparison

For the self-employed US citizen or Green Card holder residing in Hong Kong, the choice between a Solo 401(k) and a SEP IRA is not merely a question of contribution limits. It is a decision that intersects with the US Internal Revenue Code’s treatment of foreign-source income, the mechanics of the Foreign Account Tax Compliance Act (FATCA), and the practical realities of maintaining US retirement accounts from a Hong Kong address. With the SECURE 2.0 Act of 2022’s provisions on Roth catch-up contributions and employer matching for student loan payments now fully phased in for the 2025 and 2026 tax years, the calculus for these plans has shifted materially. For the Hong Kong-based self-employed, who often navigate a tax environment with no capital gains tax and a territorial income tax system, the ability to defer US tax on retirement savings—or to build a Roth balance for tax-free qualified withdrawals—becomes a critical component of long-term cross-border financial planning. This analysis examines the structural, contribution, and compliance differences between the Solo 401(k) and the SEP IRA, with specific guidance for the US person living in Hong Kong.

Contribution Limits and the Mechanics of Foreign Earned Income

The Solo 401(k): Higher Ceilings, Catch-Up, and Roth Options

The Solo 401(k), also known as an Individual 401(k), offers the highest contribution ceiling among retirement plans available to the self-employed. For the 2025 tax year, the total contribution limit is USD 70,000 (USD 23,500 in employee elective deferrals plus up to 25% of net self-employment income as an employer profit-sharing contribution, capped at the overall limit). For individuals aged 50 or older, a catch-up contribution of USD 7,500 applies, raising the total to USD 77,500. Under SECURE 2.0, for 2025 and later years, employees aged 60-63 may make a higher catch-up contribution of the greater of USD 11,250 or 150% of the regular catch-up amount (USD 11,250 in 2025), provided the plan adopts this provision.

For the Hong Kong-based self-employed person, the key interaction is with the Foreign Earned Income Exclusion (FEIE) under IRC § 911. If the taxpayer elects the FEIE, their foreign earned income up to the annual exclusion amount (USD 126,500 for 2024, indexed for inflation in 2025) is not subject to US federal income tax. However, the Solo 401(k) employee deferral is calculated on the individual’s compensation as defined by the plan. If the taxpayer’s foreign earned income is entirely excluded under the FEIE, the IRS has taken the position that such excluded income is not “compensation” for purposes of making employee elective deferrals to a Solo 401(k). This is a critical nuance: the elective deferral portion (the USD 23,500) cannot be funded from FEIE-excluded income. The employer profit-sharing contribution (the 25% portion) is calculated on net self-employment income, which is reduced by the FEIE election. The practical consequence is that a Hong Kong-based self-employed individual who excludes all their income under the FEIE may find their Solo 401(k) contribution capacity severely limited or entirely unavailable for the employee deferral piece.

A workaround exists: the taxpayer can elect not to use the FEIE and instead claim the Foreign Tax Credit (FTC) under IRC § 901 for Hong Kong salaries tax paid. This preserves the full amount of foreign earned income as “compensation” for Solo 401(k) purposes, allowing the maximum employee deferral. The decision hinges on the taxpayer’s effective tax rate in Hong Kong (a maximum of 15% under the standard rate) versus the US marginal rate. For a taxpayer in a high US bracket, the FTC may be more beneficial overall, and it unlocks the Solo 401(k)’s full capacity.

The SEP IRA: Simplicity with a Lower Ceiling

A Simplified Employee Pension (SEP) IRA allows an employer to contribute up to 25% of the employee’s compensation, capped at USD 70,000 for 2025. For a self-employed individual, the calculation is on net self-employment income (Schedule SE), reduced by the deduction for one-half of the self-employment tax. The SEP IRA does not permit employee elective deferrals; all contributions are made by the “employer” (the self-employed individual). Catch-up contributions are not available in a SEP IRA.

The SEP IRA’s interaction with the FEIE is more straightforward but still limiting. Since all contributions are employer-funded, they are calculated on the individual’s net earnings from self-employment. If the FEIE is elected, those net earnings are excluded from US gross income. The IRS has consistently held that contributions to a SEP IRA are not permitted if the compensation on which they are based is excluded under IRC § 911. The contribution itself is a deduction against net earnings, but if those earnings are already excluded, there is no taxable income against which to deduct. As a practical matter, a self-employed individual in Hong Kong who uses the FEIE will likely have a zero or near-zero contribution limit for a SEP IRA.

A taxpayer who forgoes the FEIE and uses the FTC can make the full SEP IRA contribution, up to 25% of net self-employment income, capped at USD 70,000. This is a simpler calculation than the Solo 401(k) but offers less total contribution potential (no employee deferral component).

Compliance and Account Structure for Hong Kong Residents

Solo 401(k): The Need for a US-Based Provider and Plan Document

Establishing a Solo 401(k) requires a formal written plan document. Most major US brokerages (Fidelity, Vanguard, Charles Schwab) offer Solo 401(k) plans, but their acceptance of non-US residents as plan participants varies. A Hong Kong resident with a US mailing address (e.g., a family member’s home or a mail-forwarding service) may be able to open the account. However, the IRS requires that the plan’s trust be administered in the United States. The account itself must be held at a US financial institution that is a qualified trustee.

A critical compliance point for Hong Kong residents is the FATCA Form 8938 and the FBAR (FinCEN Form 114). The Solo 401(k) account, if held at a US financial institution, is a specified foreign financial asset for FATCA purposes if the account is not at a US branch of a US financial institution. In practice, if the account is at Fidelity or Vanguard in the US, it is a US account and not a foreign financial asset. However, the FBAR filing requirement applies to any financial account outside the United States. Since the Solo 401(k) is held in the US, it is not reportable on the FBAR. This is a significant advantage: the Solo 401(k) avoids the dual reporting burden of FBAR and FATCA.

The Solo 401(k) also allows for a Roth component. The Roth Solo 401(k) permits after-tax contributions (employee deferrals only) that grow tax-free. For a Hong Kong resident who pays no US tax due to the FEIE, Roth contributions may be appealing: the contribution is made with after-tax dollars (and the FEIE means no US tax is saved on the contribution), but all qualified distributions (including earnings) are tax-free. The SECURE 2.0 Act’s provision requiring Roth catch-up contributions for high earners (those with prior-year wages from the plan sponsor exceeding USD 145,000, indexed) takes effect in 2026. For the Hong Kong-based self-employed, this means that if their net self-employment income exceeds the threshold, any catch-up contribution must be made to the Roth account.

SEP IRA: Simplicity in Setup, Simplicity in Reporting

A SEP IRA is simpler to establish. The employer (the self-employed individual) executes a simple IRS Form 5305-SEP. The account can be opened at any US brokerage that accepts non-resident clients. The same FATCA and FBAR considerations apply: a SEP IRA held at a US institution is a US account, not reportable on FBAR, and not a specified foreign financial asset for FATCA.

The SEP IRA does not permit loans from the plan, whereas a Solo 401(k) may allow loans (up to the lesser of USD 50,000 or 50% of the vested account balance). For a Hong Kong resident who may need liquidity for a property purchase or business investment, this is a material distinction.

Withdrawal Rules, Early Distributions, and the Hong Kong Tax Angle

Early Withdrawal Penalties and Exceptions

Both the Solo 401(k) and SEP IRA are subject to the 10% early withdrawal penalty under IRC § 72(t) for distributions before age 59½, unless an exception applies. For the Hong Kong resident, the key exceptions are:

• Substantially equal periodic payments (SEPP) under IRC § 72(t)(2)(A)(iv)
• Distributions due to total and permanent disability
• Distributions for unreimbursed medical expenses exceeding 10% of AGI
• Distributions for health insurance premiums during unemployment (limited applicability for self-employed)

The Solo 401(k) offers an additional exception not available to SEP IRAs: a loan from the plan. The loan is not a taxable distribution if repaid within five years (or longer if used to purchase a primary residence). For a Hong Kong resident who may need to access funds for a down payment on a Hong Kong property, this is a significant planning tool.

The Hong Kong Tax Treatment of Distributions

Hong Kong does not impose tax on distributions from a US retirement plan. The Inland Revenue Ordinance (Cap. 112) taxes income sourced in or derived from Hong Kong. A distribution from a US 401(k) or IRA is sourced outside Hong Kong and is not subject to Hong Kong salaries tax, profits tax, or property tax. The taxpayer will report the distribution on their US Form 1040 and pay any applicable US tax, but no Hong Kong tax liability arises. This is a favorable outcome for the Hong Kong resident: the distribution is taxed only in the US, and if it is a Roth distribution, it may be entirely tax-free in both jurisdictions.

Required Minimum Distributions (RMDs)

Both plans are subject to RMD rules. Under SECURE 2.0, the RMD age increased to 73 for those turning 73 after December 31, 2022, and will increase to 75 for those turning 75 after December 31, 2032. For a Hong Kong resident who does not need the income, the RMD is an unwelcome forced distribution. The Solo 401(k) offers a potential advantage: if the individual remains self-employed and continues to work past RMD age, they may be able to delay RMDs from the current employer’s plan until they retire, provided the plan document so provides and they own less than 5% of the business. A self-employed individual who owns 100% of their business is considered a 5% owner, so this exception does not apply. For the Hong Kong self-employed, RMDs are generally unavoidable from either plan type.

Strategic Considerations for the Hong Kong-Based Self-Employed

The Case for the Solo 401(k)

The Solo 401(k) is the superior choice for a self-employed American in Hong Kong who:

• Has significant self-employment income (well above the FEIE cap) and wants to maximize tax-deferred savings
• Wants to build a Roth balance for tax-free withdrawals in retirement
• May need plan loan access for a Hong Kong property purchase or business investment
• Is willing to forgo the FEIE in favor of the FTC to preserve contribution capacity

The Solo 401(k)’s higher contribution ceiling and Roth option make it the preferred vehicle for high-earning professionals (consultants, lawyers, doctors) who have a US tax liability even after the FTC.

The Case for the SEP IRA

The SEP IRA is appropriate for a self-employed American in Hong Kong who:

• Has relatively modest self-employment income (below the FEIE cap) and plans to use the FEIE
• Wants simplicity in plan setup and administration
• Does not need plan loans
• Has no interest in Roth contributions

For the taxpayer who uses the FEIE and has zero or minimal US tax liability, the SEP IRA’s inability to accept contributions based on excluded income is a fatal flaw. However, if the taxpayer has a mix of FEIE-excluded income and non-excluded US-source self-employment income (e.g., consulting for a US client while physically present in Hong Kong), the SEP IRA can accept contributions based on the non-excluded portion.

A Hybrid Approach

A self-employed individual can maintain both a Solo 401(k) and a SEP IRA, provided the total contributions across all plans do not exceed the annual addition limit (USD 70,000 for 2025, plus catch-up). However, the employer profit-sharing contribution is aggregated across all plans. If the individual has a SEP IRA at a prior employer, contributions to the Solo 401(k) as an employer must be reduced accordingly. For the Hong Kong-based self-employed with a single business, maintaining only one plan is simpler and avoids aggregation errors.

Actionable Takeaways

1. For a self-employed American in Hong Kong with income exceeding the FEIE cap (USD 126,500 for 2024), the Solo 401(k) is the preferred vehicle, allowing up to USD 70,000 in total contributions for 2025 (USD 77,500 with catch-up) by forgoing the FEIE and using the Foreign Tax Credit instead.
2. A taxpayer who elects the FEIE cannot make employee elective deferrals to a Solo 401(k) or employer contributions to a SEP IRA, as the excluded income does not constitute “compensation” for retirement plan purposes under IRS guidance.
3. The Solo 401(k) permits plan loans of up to USD 50,000 or 50% of the vested balance, providing a liquidity option unavailable in a SEP IRA—a relevant feature for Hong Kong residents who may need access to funds for a property down payment.
4. Both plans are held at US financial institutions and are not reportable on FBAR or as specified foreign financial assets on FATCA Form 8938, simplifying annual US compliance for the Hong Kong resident.
5. Roth contributions to a Solo 401(k) are particularly advantageous for a Hong Kong resident who pays little or no US tax due to the FEIE, as the after-tax contribution grows tax-free and qualified distributions are tax-free in both the US and Hong Kong.

本文不構成稅務建議。涉及個人稅務情況請諮詢持牌會計師或稅務師。
This does not constitute tax advice. Consult a licensed CPA or tax advisor for your specific situation.