The 4% Rule for International Retirees: Does It Still Work?

Few concepts in retirement planning have achieved the status of a simple rule of thumb as widely cited as the 4% rule. The idea — that a retiree can withdraw 4% of their portfolio in the first year of retirement, adjust that sum annually for inflation, and be virtually certain of not running out of money over a 30-year retirement — has guided financial planning advice for three decades.

But the 4% rule was built on American data, at a specific period in financial history, for a retirement of a specific duration. For internationally mobile retirees drawing income from multi-currency portfolios while living in countries with different inflation rates and tax regimes, applying it uncritically is a significant planning error.

This guide examines the origins of the rule, its assumptions, where it breaks down for international retirees, and what a more rigorous alternative looks like.

The Origins of the 4% Rule

The 4% rule originates from a 1994 research paper by financial planner William Bengen, often called the "Bengen study." Bengen analysed historical US stock and bond returns from 1926 onwards and calculated what withdrawal rate would have survived all historical 30-year periods without the portfolio being exhausted.

His conclusion: a portfolio of 50–60% equities and 40–50% bonds could sustain a 4% initial withdrawal rate, adjusted annually for US CPI inflation, over every 30-year period in the historical data including the Great Depression and the inflationary 1970s.

Subsequent research by Cooley, Hubbard and Walz ("the Trinity Study") extended and broadly confirmed this finding, expressing it in terms of "portfolio success rates" across historical scenarios. The 4% rule entered mainstream financial planning guidance.

The Assumptions Embedded in the Rule

Before applying the 4% rule, it is essential to understand its embedded assumptions — all of which may not hold for a given international retiree:

1. US-based historical returns. The original research used exclusively US equity and bond returns. The US stockmarket has been the world's best-performing major market over the 20th century. A globally-weighted portfolio with higher allocations to non-US markets would have produced somewhat different (often lower) historical returns in many periods.

2. A 30-year retirement. The rule was designed to survive 30 years. A retiree at 60 in good health may face a 35–40 year retirement. The failure rate of a 4% withdrawal rate increases meaningfully over longer periods.

3. US inflation. The annual inflation adjustment was based on US CPI. Retirees spending in other currency zones face different local inflation rates. In recent years, the UK experienced an inflation peak exceeding 11% (2022–2023). If local inflation significantly exceeds the assumed US CPI adjustment, real purchasing power erodes faster than the rule anticipates.

4. No tax. The original research was generally modelled on gross returns and gross withdrawals. Tax on pension income, capital gains, or investment returns in the country of residence reduces the net withdrawal available for spending, requiring a higher gross withdrawal rate to achieve the same net income — effectively pushing the safe rate below 4%.

5. No charges. Investment management fees, adviser charges and platform costs reduce portfolio returns. A total expense ratio of 1% per annum is sufficient to materially reduce the sustainable withdrawal rate.

6. A single-currency, domestic portfolio. The rule assumes a portfolio in one currency being spent in the same currency. Currency risk is not addressed.

7. A static asset allocation. The rule typically assumes a fixed allocation throughout retirement.

Where the Rule Breaks Down for International Retirees

The Valuation Problem

Research by Kitces, Pfau and others has shown that the safe withdrawal rate at the start of retirement is highly sensitive to the starting valuation of the equity market. When equities are highly valued — as measured by cyclically adjusted price-to-earnings ratios (CAPE) — subsequent 10-year returns have historically been lower, reducing the safe withdrawal rate below 4%.

As of 2026, US equity valuations by CAPE measures remain elevated by historical standards. This does not mean a market crash is imminent — valuations can remain high for extended periods — but it does mean that a retirement starting in 2026 with a US-heavy equity portfolio faces a statistically higher probability of a poor sequence of returns than historical averages suggest.

Currency Risk

A UK retiree with a sterling-denominated portfolio living in the eurozone spending in euros faces two layered return risks: investment returns in sterling, and sterling/euro exchange rate movements. If sterling depreciates by 20% over a decade (as it broadly did following the 2016 Brexit referendum), the real value of the sterling income stream in euros falls by 20% regardless of investment returns.

The 4% rule offers no guidance on managing this currency layer of risk.

Higher Realistic Costs

For internationally mobile retirees in Western Europe or the Gulf, living costs (particularly private healthcare) are sufficiently high that the 4% rule implies a larger required portfolio than many appreciate. If your annual spending requirement is £80,000, you need a portfolio of £2,000,000 to apply a 4% rule. Add private health insurance, international travel and housing costs and the target number may be significantly higher.

Portfolio Size and Concentration

The 4% rule assumes the portfolio is invested in a relatively liquid, diversified manner. Internationally mobile retirees with significant illiquid assets — property portfolios, business interests, QROPS in less liquid structures — cannot straightforwardly apply a 4% rule to the whole picture. The investable portfolio may be smaller than total net worth.

The Impact of Early Poor Returns

As discussed in our separate guide on sequence of returns risk, the 4% rule's success in historical research depended on average long-term returns. A severely unfavourable sequence early in retirement — two or three consecutive years of large negative returns — can permanently impair a 4% withdrawal plan in a way that the historical data masks, because the data averages across all starting years.

What Rate Is More Appropriate?

Given these limitations, what is a more appropriate withdrawal rate for internationally mobile retirees as of 2026?

Most current research suggests that a rate of 3.0–3.5% is more robust for retirees starting in high-valuation environments with long retirement horizons (35+ years). This "lower and safer" position reflects:

• Elevated equity valuations
• Lower expected bond returns in a post-zero-interest-rate environment
• Longer average retirements due to increased longevity
• Higher costs and taxes for many internationally mobile retirees

For retirees who can maintain a degree of spending flexibility — reducing discretionary expenditure in poor market years — a dynamic approach can support a somewhat higher initial rate. Research by Pfau suggests that a flexible withdrawal strategy with guardrails can allow starting rates closer to 4.5–5% while maintaining high sustainability, provided that spending cuts are accepted when portfolio performance is poor.

The Guardrails Approach

One practical alternative to a fixed withdrawal rate is the "guardrails" approach, developed by financial planner Jonathan Guyton:

• Set an initial withdrawal rate (say 4.5%)
• If the portfolio falls such that the current withdrawal represents a higher percentage of current portfolio value than the initial rate plus a threshold (say more than 5.5%), reduce withdrawals by 10%
• If the portfolio rises such that the current withdrawal represents a lower percentage than the initial rate minus a threshold (say less than 3.5%), increase withdrawals by 10%

This dynamic mechanism automatically adjusts withdrawals to market conditions, reducing sequence risk while allowing retirees to benefit from strong portfolio performance. It requires the willingness to accept genuine spending cuts in bad years, which is why the floor-and-upside strategy (securing essential costs from guaranteed sources) is a useful complement.

Practical Guidance for International Retirees

1. Do not apply 4% uncritically. For a retirement starting in 2026 with a long time horizon and significant non-US equity exposure, a base rate of 3–3.5% provides more robust planning.

2. Model tax explicitly. Calculate the required gross withdrawal to achieve your desired net income after tax in your country of residence. This may require a higher gross withdrawal rate.

3. Account for currency risk. If your assets and spending are in different currencies, model the currency risk explicitly rather than assuming it away.

4. Build in flexibility. A plan that allows withdrawal rates to flex in response to portfolio performance is more sustainable than a fixed rate.

5. Maintain a cash buffer. Short-term spending should not depend on selling growth assets. Holding 12–24 months of essential expenditure in cash provides resilience against forced selling in market downturns.

6. Review annually. The sustainability of your withdrawal rate should be reviewed each year against actual portfolio performance, inflation, and changes in your spending requirements.

7. Integrate guaranteed income sources. State pensions, defined benefit income, and annuities reduce the proportion of spending that must be funded from the invested portfolio, effectively increasing the safety of the overall plan even if the withdrawal rate from the invested pot looks high.

A Note on Complexity

The 4% rule's popularity stems partly from its simplicity. Complex models are more accurate but harder to execute and easier to abandon under stress. An adviser-supported framework — combining a broadly sustainable withdrawal rate with a cash buffer, flexible spending and a clear annual review process — tends to outperform both rigid adherence to a rule of thumb and overly complex models that generate false precision.

How Global Investments Can Help

At Global Investments, we help internationally mobile retirees design and manage sustainable withdrawal strategies that account for their full picture: multiple asset pools, multiple currencies, international tax obligations, and the genuine uncertainties of a long retirement.

We do not apply rules of thumb without analysis. Every retirement income strategy we build is based on lifetime cash flow modelling, stress-tested across a range of market, inflation and currency scenarios, and reviewed regularly throughout retirement.

If you would like to understand whether your planned or current withdrawal rate is sustainable — and how to structure your drawdown most efficiently — we would be glad to discuss your situation in detail.

Contact us to speak with one of our senior advisers.

The value of investments and the income from them can fall as well as rise. Past performance is not a reliable indicator of future results. Tax treatment depends on individual circumstances and may change. This guide is for information purposes only and does not constitute regulated financial advice. Seek qualified regulated advice before making any decisions about retirement income strategy.