Is the 4% rule still relevant for retirement planning?

by Sponsored by Discovery Invest 42 views0

Is the 4% rule still relevant for retirement planning?

Traditionally, financial advisers, savers and retirees have relied on the so-called “4% rule” when working out how much to save for retirement and/or what kind of annual income retirement savings would provide. The rule was first proposed by Californian financial planner William Bengen in the 1990s.

The theory of the 4% rule

Simply put, the rule says that that if retirees withdraw 4% of their savings annually (adjusting this amount for inflation every year thereafter), their nest egg will last at least 30 years. The rule also requires that retirement savings are split equally between shares and bonds. 


This method is also used to determine the lump sum investors need when they retire in order to provide an acceptable annual income.

For example, assume you are retiring today with a final salary of R480 000 a year. You need a “replacement ratio” of 90% of your final salary. Ninety percent of R480 000 is R432 000. In order to ensure that you do not use all your saved retirement capital in 30 years, R432 000 should be 4% of your total savings. This means you would need R10.8-million saved in order to draw 4% or R432 000 annually. Put another way:

  1. You need R432 000 a year (90% of R480 000).
  2. R432 000 must be 4% of your total savings at retirement if you don’t want to deplete your nest egg.
  3. R432 000 is 4% of R10.8 million
  4. Therefore, you need R10.8 million saved at retirement in order to give you R432 000 a year.

Does it have relevance in a new century?

This retirement theory is not without its critics, however. Those who question the 4% rule’s relevance say it doesn’t take into account issues such as taxes or varying investment horizons, and also observe that financial conditions when the rule was formulated were very different to the reality in this century. For example, Bengen’s rule is based on the average long-term annual returns (since 1926!) of shares and bonds being 10% and 5.3%, respectively.

 “The 4% rule started in the US in the 1990s when interest rates were a lot higher. With rates at an all-time low, the rule has broken down there – another reason to not use rules in planning,” says Craig Gradidge, investment specialist/director at Gradidge-Mahura Investments. “In South Africa, rates and dividend yields are low, but still high enough to sustain the rule, but that could also change in time – and highlights the pitfalls of following any rules when planning for retirement.”

And a 2010 paper by Wade Pfau pointed out that the “US enjoyed a particularly favourable climate for asset returns in the twentieth century” and argued that “from an international perspective, a 4% real withdrawal rate is surprisingly risky.”

Tracy Jensen, Product Architect at 10X Investments, says although “the 4% rule still applies to retirement investing “, it needs to be applied differently in South Africa: “Whilst the 4% rule still applies to retirement investing, South Africa is unique in the sense that regulation restricts the income drawn each year from 2.5% to 17.5% of your investment balance. As a result, investors could have sufficient money to draw the income they desire but are restricted once they reach the 17.5% cap. Therefore, an adaptation of the rule is required in our context.”

Gradidge also adds that while the basis of the 4% rule is sound, it still might not be relevant to many would-be retirees: “The 4% rule is simple mathematics; the less you draw from your capital, the longer the capital will last. Given historical data, the 4% rule suggests that capital can last into perpetuity if the investor only withdraws 4% of capital as income. Mathematically, this is true. Practically, however, the majority of people have not saved sufficient capital to allow them to take advantage of the mathematics.”

A broad guideline

And so, says Jensen, the 4% rule is “more of a broad guideline to help people make decisions in a complex environment” rather than a hard-and-fast rule when working out how much of your retirement income you can spend.

The Association for Savings & Investment South Africa (Asisa) has also offered guidelines on the issue of safe withdrawal amounts (or drawdowns) from investment-linked living annuities and produced the table below, which helps indicate how many years it is likely to take before your pension starts declining significantly.

Using the table above, someone who earns 7,5% on their investment and uses a drawdown rate of 7,5% can expect to receive a real level of income (that takes inflation into account) for 10 years before their level of income starts to quickly diminish.


Perhaps the last word on the subject should go to Bengen himself. In an interview with the New York Times, his advice to those saving for retirement is perhaps applicable to every person saving for retirement: “Go to a qualified adviser and sit down and pay for that,” he said. “You are planning for a long period of time. If you make an error early in the process, you may not recover.”


For more information on investing for retirement, speak to your financial adviser.

This article is part of an investment series by Discovery Invest.

Discovery Invest is an authorised financial services provider. Registration number 2007/005969/07. For more information on Discovery Invest, contact your financial adviser.

This material is provided for educational purposes only and should not be construed as investment advice or an offer or solicitation to buy or sell investment funds.