The 4% Rule Explained: How Much Do You Need for Retirement?

The 4% rule is a rule of thumb for drawing down investment assets in retirement. It suggests withdrawing 4% of the portfolio's initial value in the first year and adjusting that withdrawal amount for inflation in subsequent years. The aim is to preserve the purchasing power of the withdrawals over an extended period.

The rule can also help investors estimate how much capital they may need to generate additional monthly retirement income. However, it does not guarantee that a portfolio will last for 30 years, nor does it ensure that the initial capital will be preserved. Capital-market performance, the equity allocation and the timing of potential losses all play an important role.

How does the 4% rule work, what risks should investors consider and how can it be incorporated into retirement planning?

• What is the 4% rule?
• How much capital do you need for additional retirement income?
• How safe is the 4% rule?
• What is sequence-of-returns risk under the 4% rule?
• What equity allocation is appropriate under the 4% rule?
• What should investors in Germany consider when applying the 4% rule?
• How can a retirement withdrawal plan be implemented in practice?

The 4% rule determines how much money is withdrawn from an investment portfolio at the start of retirement. The initial withdrawal is equal to 4% of the portfolio's value. In subsequent years, the withdrawal is not recalculated as a fixed percentage of the current portfolio value. Instead, the original withdrawal amount is adjusted for inflation.

A simple example illustrates how this works. With an initial portfolio of EUR 500,000, an investor could withdraw EUR 20,000 in the first year. This is equivalent to approximately EUR 1,667 per month before tax. If consumer prices rise by an assumed 2%, the withdrawal would increase to EUR 20,400 in the second year. With another 2% increase in inflation, the third-year withdrawal would be EUR 20,808.

In this example, the withdrawal therefore increases regardless of whether the portfolio has generated gains or losses in the meantime. Assuming the portfolio remains sufficiently funded, this approach is designed to maintain the purchasing power of the planned withdrawals.

It is important to distinguish this approach from a strategy that withdraws 4% of the current portfolio value each year. Under such a strategy, the amount withdrawn would fluctuate with the value of the portfolio. If the portfolio were worth only EUR 400,000 in the second year, for example, a 4% withdrawal would amount to EUR 16,000. Under the classic 4% rule, the planned withdrawal would still be EUR 20,400.

The classic 4% rule therefore provides greater predictability of income, but it does not automatically respond to falling portfolio values. This can affect how long the portfolio is able to sustain withdrawals.

The 4% rule provides a straightforward way to estimate the amount of capital required to generate additional retirement income. The desired annual withdrawal is divided by 0.04. In other words, the required starting capital is equal to 25 times the annual withdrawal requirement.

An investor seeking to withdraw EUR 1,000 per month would therefore need EUR 300,000 under this calculation. For a monthly withdrawal of EUR 2,000, the required capital would rise to EUR 600,000. For EUR 3,000 per month, the corresponding amount would be EUR 900,000.

These figures are indicative calculations only. They do not take account of an investor's individual tax position or the actual future performance of the portfolio. Nor do they guarantee that withdrawals can be sustained for any particular period.

It is also important to consider which expenses are already covered by other sources of income. The difference between the amount required to fund living expenses and the income already available represents the retirement income gap that needs to be financed.

Statutory and occupational pension income, rental income and other sources of income can reduce this gap. When calculating the shortfall, both income and expenditure should be considered on a comparable basis, particularly after taking account of the relevant taxes and contributions.

Not all assets are immediately available to fund regular withdrawals. An owner-occupied property, for example, may reduce ongoing housing costs but cannot be used to fund portfolio withdrawals in the same way as liquid financial assets unless it is sold or otherwise monetised.

The key question is therefore not simply how much total wealth an investor has accumulated, but how much of that wealth is actually available to fund retirement.

The 4% rule can be traced back to research published by US financial planner William Bengen in 1994. He analysed historical equity and bond market returns to assess the level of regular withdrawals that a portfolio could have supported over extended periods.

The Trinity Study, published in 1998, explored the same issue using historical US capital-market data and examined different withdrawal rates and portfolio allocations. As a result, a 30-year period became an important benchmark in retirement planning.

Under the assumptions used in these studies, an initial withdrawal rate of around 4% produced favourable historical outcomes. This should not, however, be interpreted as a guarantee of future capital-market performance.

Another important point is the definition of "success". In many withdrawal studies, a strategy is considered successful simply if the portfolio has not been completely depleted by the end of the period under review. This is not the same as preserving the initial capital or maintaining its purchasing power indefinitely.

The intended withdrawal period also matters. While 30 years is frequently used as a benchmark, an individual's retirement may last significantly longer. Investors who retire early, or couples planning over a long joint retirement horizon, may therefore need to consider a longer period.

How long, for example, EUR 500,000 would last with an initial annual withdrawal of 4% cannot be determined reliably without assumptions about future investment returns, inflation and the pattern of withdrawals.

A high average equity return does not automatically solve this problem. Even if an equity market were assumed to generate a long-term return of 7% or 8%, this would not imply that withdrawals of 6% or 7% could reliably be sustained. A mixed portfolio may generate different returns, while inflation, costs and taxes also affect the amount ultimately available to the investor.

Most importantly, capital-market returns do not occur at a constant rate. Strong and weak market years alternate, while living expenses continue throughout retirement. Average returns alone therefore do not determine how long a portfolio will last.

Sequence-of-returns risk describes the risk that the order in which gains and losses occur can have a material impact on the long-term development of a portfolio.

This is particularly relevant when investors are making regular withdrawals. If markets fall early in retirement, more investment units may have to be sold to fund the same level of spending. Those units are then no longer available to participate in a subsequent market recovery.

Two portfolios each start with EUR 500,000. At the beginning of every year, EUR 20,000 is withdrawn. The remaining portfolio then rises or falls in line with that year's investment return.

Portfolio A records a return of -20% in the first year, +25% in the second year and +10% in the third year.

Portfolio B experiences exactly the same annual returns, but in a different sequence: +10% in the first year, +25% in the second year and -20% in the third year.

After three years, Portfolio A is worth EUR 478,500, while Portfolio B is worth EUR 492,000.

Although both portfolios experienced exactly the same annual returns and the same amounts were withdrawn, their final values differ by EUR 13,500.

Without withdrawals, both portfolios would have ended with exactly the same value of EUR 550,000. The example deliberately excludes inflation, costs and taxes. Its sole purpose is to illustrate the impact of the sequence in which investment returns occur.

Sequence-of-returns risk is especially relevant in the years immediately before and after retirement.

During the later stages of accumulation, investors have often already built up a substantial portfolio but have relatively little time remaining to make additional contributions. Significant market losses can therefore affect the planned timing of retirement.

During the early years of the withdrawal phase, there is an additional challenge: living expenses increasingly have to be funded from the existing portfolio. If regular asset sales coincide with a prolonged period of negative returns, the portfolio may decline significantly.

Research therefore often treats a period of roughly ten years before and ten years after retirement as particularly sensitive. This should not be interpreted as a fixed risk boundary. The impact of market losses depends on the individual portfolio, ongoing contributions and withdrawals, and subsequent market performance.

Sequence-of-returns risk does not mean that every market decline early in retirement will inevitably result in the portfolio being depleted prematurely. Rather, it explains why two investors with the same starting wealth and similar long-term average returns can experience very different outcomes.

The 4% rule does not imply a universally optimal equity allocation. How assets are divided between equities, bonds and liquidity affects both the portfolio's long-term return potential and the degree of volatility experienced during the withdrawal phase.

A low equity allocation does not automatically mean a lower risk of running out of money prematurely. Equities offer long-term growth potential that can help offset ongoing withdrawals and the erosion of purchasing power caused by inflation. If this growth component is largely absent, capital may be depleted more rapidly.

A high equity allocation, on the other hand, generally involves greater fluctuations in portfolio value. If significant losses occur shortly after retirement, regular withdrawals can amplify the decline in the remaining capital.

A mixed portfolio seeks to combine these different characteristics. Equities provide exposure to the long-term growth of companies, while bonds can generate ongoing income and contribute to portfolio stability. Their own risks must nevertheless be taken into account.

For bonds in particular, duration and credit quality are important. If market interest rates rise, for example, long-dated bonds can experience substantial price declines. Equities and bonds can also suffer losses at the same time.

An additional liquidity buffer can help organise regular payments without requiring equities to be sold for every withdrawal. However, holding liquidity does not eliminate sequence-of-returns risk and should be considered as part of the investor's overall asset allocation.

Investors may also wish to review their portfolio allocation several years before the planned start of retirement. Rather than making a major change to the equity allocation only when retirement begins, the portfolio can be adjusted gradually to reflect future withdrawal requirements.

The appropriate equity allocation ultimately depends on factors including the planned withdrawal horizon, other sources of income and the investor's ability to tolerate temporary losses or lower withdrawals.

The original research underlying the 4% rule was based on historical US capital-market data. Its findings cannot therefore be transferred directly to investors in Germany. Differences in currencies, inflation, capital-market performance, investment costs and taxation can all affect retirement withdrawal planning.

One particularly important distinction is between the amount withdrawn from an investment portfolio and the taxable gain realised when assets are sold.

When an investor sells units in an investment fund, the entire sale proceeds are generally not subject to tax. Among other factors, the taxable amount depends on the difference between the sale proceeds and the tax-relevant acquisition cost of the units sold.

Depending on the fund, the German partial exemption, the available saver’s allowance and any advance lump sums already taken into account can also affect the investor's tax liability.

For qualifying equity funds held by private investors, 30% of income is generally exempt from tax.

For multi-asset funds that are treated as mixed funds for German tax purposes, the partial exemption is 15%.

If, however, a multi-asset fund meets the tax requirements for classification as an equity fund, a partial exemption of 30% may also apply.

As a result, the amount that needs to be sold from a portfolio to meet a particular net income requirement may be higher than the withdrawal originally calculated.

Other sources of income also need to be taken into account correctly. German statutory pension income is subject to different tax rules from gains realised on the sale of fund units. Health and long-term care insurance contributions may also vary depending on the individual's insurance status.

Inflation is another important factor. If an individual's living costs rise faster than pension income and other sources of income, the retirement income gap may widen more rapidly than the general rate of inflation. Simply increasing the original withdrawal each year in line with the consumer price index will not necessarily capture this additional funding requirement in full.

For investors in Germany, the 4% rule should therefore primarily be regarded as a starting point. Individual tax circumstances and the broader financial situation also need to be incorporated into retirement planning.

A retirement withdrawal plan links an investor's ongoing income requirements with the available investment assets and a defined approach to regular withdrawals.

Consider a household with EUR 450,000 in investable assets at retirement and monthly living expenses of EUR 3,000. After the assumed deductions, EUR 1,500 per month is available from the statutory pension.

This leaves a retirement income gap of EUR 1,500 per month, or EUR 18,000 per year. Relative to the starting portfolio of EUR 450,000, this corresponds to an initial withdrawal rate of 4%.

However, this calculation does not yet take account of the potential tax implications of selling investments. If the household needs to receive EUR 1,500 per month after tax, the required sale proceeds may be higher. Nor does the calculation demonstrate that this level of withdrawal can necessarily be sustained over the long term.

An important first step in implementing a withdrawal plan is therefore to determine how the portfolio should be allocated across equities, bonds, other asset classes and liquidity. A liquidity buffer can, for example, be used to make regular payments without having to sell investments for every monthly withdrawal.

The chosen asset allocation should also be reviewed regularly. Rebalancing restores the portfolio's intended target weights across individual asset classes.

Distributions and necessary asset sales can both be incorporated into retirement withdrawal planning. However, fund distributions form part of the total return of an investment. They are not an additional source of return on top of the fund's performance.

Flexible withdrawal strategies can also be considered alongside the classic 4% rule.

Under a fixed-percentage withdrawal strategy, a defined percentage of the current portfolio value is withdrawn each year. If the portfolio falls in value, the withdrawal automatically declines as well. This may help limit capital depletion but can also result in substantial fluctuations in the investor's available income.

Another approach is to suspend the annual inflation adjustment after years in which the portfolio records losses. The nominal withdrawal initially remains unchanged, but its purchasing power falls if prices continue to rise.

More sophisticated approaches use predefined adjustment thresholds, often referred to as guardrails. If a particular threshold is breached, withdrawals are reduced or, where appropriate, increased.

Flexible withdrawal approaches can help reduce capital depletion. However, any benefit to the portfolio comes from lower withdrawals rather than from an automatically higher investment return.

The key consideration is therefore which elements of spending are essential and which can be adjusted if necessary. Investors who depend on a fixed minimum level of income for their living expenses have less flexibility to reduce withdrawals.

A robust retirement withdrawal plan should therefore not focus solely on maximising the initial level of income. It is equally important to consider whether essential expenditure can continue to be funded for as long as possible, including during unfavourable capital-market environments.

The 4% rule provides a simple starting point for estimating the amount of capital required in retirement.

At an initial withdrawal rate of 4%, the required starting portfolio is equal to 25 times the annual amount that needs to be withdrawn.

Whether the portfolio will actually last for the desired period depends on a range of factors. In addition to the level of withdrawals, the sequence of investment returns, the equity allocation, inflation, costs and taxes all play an important role.

The 4% rule should therefore not be regarded as a promise of a particular level of retirement income or of permanent capital preservation. Instead, it can serve as a starting point for a broader retirement withdrawal plan that takes account of the investor's income gap, investment horizon and ability to adapt withdrawals over time.

The 4% rule is only one way of structuring regular withdrawals from an investment portfolio. The following articles explore additional aspects of retirement withdrawal planning.

• Withdrawal plans: planning regular withdrawals from your portfolio

  What should investors consider before they begin drawing down their assets, and which withdrawal strategies are available? Our overview explains the key considerations, including income requirements, risk tolerance, portfolio structure and different approaches to withdrawals.

   

• Monthly distributions from investment funds

  Monthly distributions can provide a way of generating regular payments from an investment. However, investors should consider not only the level of distributions, but also the long-term development of the portfolio, inflation and risk.

   

• Distributing or accumulating funds?

  What is the difference between distributing and accumulating funds, and what role can the treatment of investment income play when planning regular withdrawals?