Currency Risk and Your FI Number as an Expat

Your FI number is denominated in euros: so much per year to live on in the Netherlands. But if a chunk of your wealth still sits in a 401(k), a UK pension, or a brokerage account back home, that wealth is denominated in USD or GBP. The 4% rule and every generic FIRE calculator quietly assume your portfolio and your spending live in the same currency. For an expat with wealth split across two currencies, that assumption is false — and it introduces a risk those tools never model: your home currency can weaken against the euro in exactly the year you start drawing down, cutting your real spending power here even if your portfolio's return, measured in its own currency, looks fine.

Why "it'll average out" stops working once you're spending

During accumulation, currency swings are close to noise: you're adding money monthly, your horizon is a decade or more, and an unfavorable FX cycle in year three has years to reverse before it matters. "Leave it in USD, it evens out over time" is a reasonable bet when you're not touching the money.

Drawdown removes that luxury. Once you're withdrawing every year to cover EUR spending, you're converting on whatever terms the market offers that year, not an average of years you haven't lived yet. This is sequence-of-returns risk applied to a second variable: a market drop early in retirement does outsized damage because you're selling depreciated assets with less time to recover. An unfavorable currency move does the same thing a different way — it doesn't touch your return at all, it just shrinks how many euros that return converts into.

The dangerous case is both at once: a US-heavy portfolio down 15% in a bad market year, with the dollar also down 10% against the euro, isn't a 15% problem — it's a compounded hit to your EUR spending power right when you have the least ability to wait it out. Standard safe-withdrawal-rate research doesn't model this: it assumes portfolio and spending currency match. Yours might not.

Box 3 moves with the exchange rate too

There's a second, less obvious place FX shows up: your wealth tax bill. Foreign-currency assets are converted to euros for Box 3 purposes as of the peildatum (1 January), regardless of what currency they're held in — so your taxable base, and the bill itself, can shift year to year purely from exchange-rate movement, the underlying holding unchanged. A strong dollar year inflates the euro value of your 401(k) and raises your assessment; a weak dollar year does the opposite. See the Box 3 wealth tax guide for the valuation mechanics — FX is one more input unrelated to how your investments actually performed.

Three ways to respond — not one right answer

There's no single correct fix here, and this site isn't going to tell you there is. The three broad responses trade off against each other:

• Convert gradually as you approach your FI date. Shifting foreign-currency holdings toward EUR-denominated assets before drawdown reduces exposure right when sequence risk matters most. The cost: you give up diversification and lock in today's exchange rate rather than one averaged over more years.
• Hold a EUR-denominated buffer sized for a stretch of spending. The FX-specific version of the standard emergency-fund logic: keep enough EUR cash or bonds on hand to cover a year or two of spending without touching the foreign-currency portion, whatever the exchange rate is doing. It costs the deemed-return drag of holding cash under Box 3, same as any buffer, but buys the ability to wait out an unfavorable FX cycle instead of converting into it.
• Accept the exposure deliberately. Currency risk is also diversification — a split across EUR and USD (or GBP) isn't purely a liability, it's a bet uncorrelated with euro-zone conditions. The difference from doing nothing is sizing it on purpose, deciding what fraction of spending you're comfortable leaving exposed, rather than holding foreign assets because moving them felt like a chore.

None of these eliminate the risk; they redistribute it. Currency-hedged share classes exist as a fourth-ish option — fund structures designed to strip out most FX exposure from a foreign holding — but which fund, and whether the hedging cost is worth it for your mix, is a product decision this guide won't make for you.

What this changes about your number

If part of your wealth sits outside the eurozone, your real FI number isn't just "spending ÷ safe withdrawal rate" — it's that calculation plus an unhedged risk a generic calculator, and even the Box 3-adjusted FIRE math, doesn't touch. The same is true of other assumptions generic safe-withdrawal-rate guidance gets wrong here — see the partial AOW guide for another case where the standard 4% framework needs adjusting to your situation.

Currency exposure isn't a box to check once before you retire. Exchange rates move continuously, your foreign-currency balance changes in EUR terms every time they do, and the right response — convert more, hold a bigger buffer, stay exposed — can shift as your FI date nears and your tolerance for spending-currency volatility shrinks. Revisit the split each year as part of your regular financial check-in, and if the foreign-currency portion is large or structurally complicated — a 401(k) with early-withdrawal penalties, a defined-benefit pension that can't be moved — a financial advisor with real cross-border experience is worth the conversation before you lock in a drawdown plan.