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Roth Conversion Window Calculator for US Expats

US expats using the Foreign Earned Income Exclusion (FEIE) can end up with zero or near-zero US taxable income. That creates an unusual opportunity: converting traditional IRA or 401(k) assets to Roth at 7–12% effective federal tax rates — far below what the same conversion would cost if you lived stateside. This calculator estimates your bracket room and the tax cost of a proposed conversion.

The core opportunity. FEIE excludes up to $132,900 of foreign earned income from US tax (2026). After the standard deduction ($16,100 single / $32,200 MFJ), many expats have effectively zero pre-conversion taxable income. Roth conversions — unlike new contributions — require no earned income and have no income ceiling. The combination can make conversions dramatically cheaper than they would be for a US-based taxpayer.

How the FEIE Roth conversion window works

  1. FEIE removes your earned income from US taxable income. Up to $132,900 of foreign wages or self-employment income is excluded in 2026 (IRS Notice 2025-67). If your salary is $130,000 and you qualify for FEIE, that entire amount disappears from your US return.
  2. The standard deduction removes another $16,100–$32,200. For 2026, the standard deduction is $16,100 for single filers and $32,200 for married couples filing jointly. If your remaining income after FEIE is less than the standard deduction, your US taxable income is zero before any conversion.
  3. Roth conversions fill those empty brackets at a low cost. Conversions are not earned income, so FEIE does not exclude them. They are added to your AGI and taxed at ordinary rates — but starting from a very low base. A $50,000 conversion when your pre-conversion taxable income is zero costs roughly $3,800–$5,800 in federal tax, an effective rate of 7–12%.
  4. The converted money grows tax-free forever. No RMDs on Roth IRAs starting in 2024 (SECURE 2.0 § 325). No ordinary income tax on qualified withdrawals at retirement. For expats planning to retire or return to the US, Roth assets are especially valuable because they are invisible to income-based phaseouts like IRMAA, NIIT, and SS taxation.

Contributions vs. conversions: a critical distinction

FEIE destroys new Roth IRA contribution eligibility when it eliminates all of your earned income. IRA contributions require earned income not excluded under IRC § 911 — if FEIE zeroes your wages, you have no "compensation" for IRA purposes and cannot contribute (§ 219(f)(1)).

Roth conversions are different. You are not contributing new money — you are moving existing pre-tax assets (traditional IRA, rollover IRA, old 401(k) rolled to IRA) to Roth. Conversions require no earned income and have had no income ceiling since 2010. The income limit that once restricted conversions was permanently removed.

The practical result: many high-earning expats who use FEIE cannot contribute to a Roth IRA at all (their MAGI for the contribution phaseout includes the excluded income, per § 408A(c)(3)(C)(i), pushing them above the $168,000 single / $252,000 MFJ ceilings for 2026). Conversions are the only Roth door still open to them.

Important rules and traps

State income taxes

This calculator models federal tax only. California does not recognize FEIE — California taxes worldwide income regardless of where you live, and the converted amount is also subject to CA income tax at up to 13.3% if you maintain California domicile. New York applies similar logic until domicile is properly severed. Correct state domicile planning before converting is essential. See the state residency and domicile planning guide.

NIIT and the conversion-MAGI interaction

Roth conversions are not "net investment income" under § 1411 and are not subject to the 3.8% NIIT directly. But the conversion increases your MAGI, which can push existing investment income (dividends, capital gains) above the NIIT threshold ($200,000 single / $250,000 MFJ, not indexed for inflation). Plan the conversion amount with an eye on where your total MAGI lands relative to these thresholds.

Capital gains bracket creep

When you use FEIE, the IRS computes your capital gains tax rate as if the excluded income had not been excluded — it fills the lower brackets, potentially pushing capital gains from 15% to 20%. A Roth conversion adds additional ordinary income on top, which can have the same effect. If you plan to realize long-term gains in the same year as a conversion, model the combined impact carefully.

The 5-year rule

Each Roth conversion starts a separate 5-year holding period for penalty-free access to the converted principal (not the same as the 5-year rule for Roth earnings). If you are converting with the intention of accessing the funds in fewer than 5 years and are under 59½, you may owe a 10% penalty on the principal. Converting in anticipation of retirement 5+ years away sidesteps this entirely.

FTC users: is conversion still useful?

If you use the Foreign Tax Credit (high-tax countries: UK, Germany, France, Japan), your earned income stays in your AGI — FTC credits the tax but does not exclude income. Your taxable income before conversion is higher, leaving less bracket room. However, the window still opens in years with lower income: sabbaticals, career transitions, partial-year moves, or early retirement. In those years, FTC carryforwards from prior high-tax years may also offset some of the conversion tax.

Self-employment tax

FEIE does not reduce self-employment tax. If your foreign income is self-employment income, you owe SE tax (15.3% on the first $176,100 for 2026, 2.9% above that) regardless of the FEIE exclusion. The SE tax is separate from the income tax calculation in this calculator.

Related reading and tools

Model your actual conversion with an expat specialist

The optimal conversion amount depends on your state domicile situation, current and projected bracket trajectory, FTC carryforward balance, expected return date to the US, and Roth IRA contribution history. A flat-fee expat advisor can model the full multi-year conversion ladder in a single planning session.

  1. IRS Rev. Proc. 2025-32 — 2026 standard deduction ($16,100 single / $32,200 MFJ) and income tax bracket thresholds.
  2. IRS Notice 2025-67 — 2026 FEIE maximum exclusion: $132,900.
  3. Tax Foundation — 2026 Federal Income Tax Brackets — bracket thresholds cross-referenced against Rev. Proc. 2025-32.
  4. IRS Topic 559 — Net Investment Income Tax — NIIT thresholds ($200K single / $250K MFJ); not indexed for inflation.
  5. IRC § 219(f)(1) — earned income for IRA contribution purposes is reduced by amounts excluded under § 911 (FEIE).
  6. IRC § 408A(c)(3)(C)(i) — Roth IRA MAGI for contribution phaseout adds back § 911 excluded amounts.
  7. IRS — 2026 IRA and 401(k) contribution limits — IRA: $7,500 (under 50) / $8,600 (50+); 401(k): $24,500.
  8. Values verified June 2026. This calculator estimates federal income tax on a Roth conversion; it does not model SE tax, state income tax, AMT, or the capital-gains bracket creep effect of FEIE stacking.

This tool provides directional estimates only. Individual situations vary materially based on state domicile, foreign account structures, FTC carryforward balances, and multi-year income projections. Consult a qualified US expat tax specialist before executing a conversion.