Sustainable Withdrawal Rates in Retirement: What the Research Says

Thinking beyond the 4% rule

The 4% withdrawal rule has become the default shorthand for retirement income planning. It has the virtue of simplicity: take 4% of your portfolio in year one, increase it with inflation each year, and historical data suggests you will not run out of money over a 30-year retirement. For a simple case with a single balanced portfolio and a predictable retirement horizon, it is a reasonable starting point.

For high-net-worth retirees, however — who may have multiple income sources, complex tax situations, overseas assets, variable spending needs, and potentially a 35-year or longer retirement — the 4% rule is a beginning, not an answer. This guide examines what the research actually says, why it may not apply to your situation, and what more sophisticated approaches look like in practice.

The origin and limitations of the 4% rule

Bill Bengen's 1994 research analysed US historical market data from 1926 onwards and found that a 4% initial withdrawal rate from a 50/50 equity-bond portfolio had never depleted a portfolio over a 30-year period, even in the worst historical sequences (including the Great Depression and 1970s stagflation). The "Trinity Study" in 1998 extended this analysis and found a high probability of portfolio survival at the 4% rate.

The key limitations of this research for UK and internationally mobile retirees are:

The research used US market data. US equity returns over the 20th century were historically exceptional — among the highest in the world. Research using global or UK data suggests sustainable withdrawal rates closer to 3 to 3.5% in some scenarios.

The 30-year horizon may be insufficient. A healthy 60-year-old today has a significant probability of living past 90. A 35 or 40-year retirement requires a more conservative withdrawal rate — some researchers suggest 3 to 3.5% for a 40-year retirement with high confidence.

The research assumed a static portfolio. Real wealthy retirees have complex income structures: state pensions commencing years into retirement; defined benefit pensions; rental income; offshore bonds with deferred tax; business income. These change the dynamics significantly.

Finally, the research was conducted when bond yields were substantially higher. In a lower-yield environment, the traditional 60/40 bond-equity portfolio generates less income, and sequence-of-returns risk from the equity component is more pronounced.

Sequence-of-returns risk: the biggest threat in early retirement

The order of investment returns matters enormously in retirement drawdown. Consider two retirees with identical average annual returns of 7% over 20 years. One experiences strong returns in years one to five, then poor returns in years fifteen to twenty. The other experiences poor returns in years one to five, then strong returns later.

Despite identical long-run averages, the second retiree will have a much smaller portfolio. The reason: early withdrawals from a falling portfolio lock in losses permanently. There is less capital left to benefit from the recovery. This is sequence-of-returns risk.

The practical implication is that the first five to seven years of retirement are critically important. A major market decline in that window — like 2001-03 or 2008-09 — can permanently impair a retirement income plan that would have been fine without the poor sequence.

Mitigation strategies include:

A cash buffer: holding one to two years of income needs in cash or near-cash, so that equity assets do not need to be sold in a downturn. The portfolio can recover while income is drawn from the buffer.

Variable withdrawals: reducing withdrawals in poor return years, preserving the portfolio. Guardrail strategies (reducing withdrawals by a fixed percentage if the portfolio falls below a certain level) formalise this.

Annuities as sequence protection: purchasing a guaranteed income (annuity) for the early years of retirement eliminates the risk of selling equities in a downturn, while the remaining portfolio grows uninhibited by withdrawal pressure.

The floor-and-upside approach

One of the most practically elegant frameworks for retirement income planning is the "floor and upside" model. The retirement income is divided into two conceptual buckets:

The floor: guaranteed or near-guaranteed income sufficient to cover essential, non-negotiable spending — housing costs, utilities, basic food, healthcare. This is ideally provided by the state pension (the full new State Pension is around £12,548 per year — £241.30 per week — in 2026-27), any defined benefit pension entitlements, and potentially a small lifetime annuity. The floor does not depend on market performance.

The upside: everything above the floor is funded from the investment portfolio — drawdown from a SIPP or SSAS, ISA withdrawals, offshore bond income, rental income, business distributions. This layer funds discretionary spending: holidays, grandchildren's education, charitable giving, the second home.

Because the floor is secure, the retiree can afford to take investment risk with the upside layer and can tolerate market volatility without anxiety about covering essential needs. In poor market years, the discretionary upside spending can flex downwards without threatening the lifestyle fundamentals.

For wealthy retirees, the floor may be very modest relative to total income — but the framework still provides a discipline for managing the division between secure and variable income.

Tax ordering in multi-source retirement income

For high-net-worth UK retirees with multiple income sources, the sequence and mix of withdrawals matters enormously for tax efficiency:

An offshore bond can provide tax-deferred income via the five per cent annual withdrawal allowance — no tax event each year, with tax deferred until eventual surrender. This is valuable when other income sources in the same year would push the retiree into higher tax bands.

ISA withdrawals are tax-free and count for nothing in assessments of marginal tax rate, Personal Savings Allowance erosion, or Child Benefit/Personal Allowance taper calculations. They are often best used when income from other sources is already high.

SIPP drawdown is taxable as income in the year of withdrawal. Staggering pension drawdown to match the personal allowance and basic rate band — particularly in the years before the state pension begins (State Pension age is currently 66, rising to 67 between April 2026 and March 2028) — can substantially reduce lifetime income tax.

Rental income is taxable and relatively inflexible in timing. Property-related cash flows should be modelled as given and the other income sources managed around them.

The state pension cannot be deferred indefinitely without penalty, and commences automatically from state pension age unless actively deferred. Deferral increases the annual entitlement.

Longevity planning: do not run out of money

Statistics on longevity are frequently underestimated at the individual level. Among a group of 65-year-olds today, roughly one in five will live past 90. A married couple, both aged 65, have a better than even chance that at least one of them will reach 90. Planning for a 25-year retirement (to age 90) is prudent minimum; planning for 30 years or more is increasingly appropriate.

Longevity risk — the risk of outliving assets — is the mirror image of sequence-of-returns risk. One is a risk of too little early return, the other a risk of too long a life. Both are managed by the same combination: a secure income floor, a diversified growth portfolio, flexible withdrawal rules, and regular review.

Inflation is the silent destroyer of fixed retirement income. Even modest inflation of 2.5% reduces the real value of income by a third over 17 years. Income sources that do not rise with inflation — older annuities, interest from cash deposits — gradually erode living standards. Equities, index-linked bonds, property, and real assets provide varying degrees of inflation protection.

Retirement income planning should be reviewed at least annually, and certainly following significant market movements, changes to health or family circumstances, or changes in tax legislation. This is not a plan that should be set and left. Investments can fall as well as rise. This guide is for information only.

How Global Investments can help

Global Investments works with retirees and pre-retirees on constructing sustainable, tax-efficient retirement income strategies tailored to their specific circumstances — whether they are UK-based, internationally mobile, or planning to retire abroad. We model withdrawal rates across different portfolio scenarios, design the tax-ordering of income from multiple sources, and integrate the state pension, DB pension, property income, and investment drawdown into a coherent plan. Contact our retirement planning team to begin the conversation.