Sustainable Withdrawal Rates – Part 2

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Sustainable Withdrawal Rates – Part 2

As mentioned in part I: Sustainable Withdrawal Rates, estimating the correct amount to withdraw from your retirement savings is critical in ensuring you make your investments last for your entire life as well as your spouses.

Part II focuses on the various techniques that can be employed to minimize the risk associated with outliving your retirement savings. Effectively recognizing and managing the three fundamental risks you will face in retirement; market risk, inflation risk and longevity risk, will greatly increase your confidence about your financial security in your golden years.


Establishing a comfort level with uncertainty

As noted previously, setting a sustainable withdrawal rate requires many assumptions and forecasts about what will happen in the future. Changing any of the variables may increase or decrease the level of certainty about whether your portfolio will last as long as you need it to. Increasing certainty about the outcome may require reducing your withdrawal rate or revising your investment strategy. Conversely, increasing your withdrawal rate, especially in the early years of retirement, may also increase the odds that your portfolio will be depleted during your lifetime.

The challenge is to balance all factors so that you have an acceptable level of certainty about the portfolio’s longevity consistent with providing the level of income needed over your expected lifetime and the risk you’re willing to take to provide it.

One increasingly common method for estimating the probability of success is the Monte Carlo simulation. This technique uses a computer program that takes information about your portfolio and proposed withdrawal strategy, and tests them against many randomly generated hypothetical returns for your portfolio, including best-case, worst-case, and average scenarios for the financial markets. Based on those aggregated possibilities, the program calculates your portfolio’s probability of success. Monte Carlo simulations also allow you to revise assumptions about lifespan, withdrawal rates, and asset allocation to see how changing your strategy might affect your portfolio’s chances. Though the process offers no guarantees, it does take into account potential fluctuations in your portfolio’s year-to-year returns. The result is a more sophisticated analysis than simply establishing a withdrawal rate based on a constant rate of return on your investments over time.

Some retirement income strategies tackle the question of uncertainty by including not only income sources that pay variable amounts, but also sources that provide relatively fixed or stable income, or lifetime income that is guaranteed. Just remember that the purchasing power of any fixed payment amounts can be eroded over time by inflation.

Once you’ve established an initial withdrawal rate, you probably should revisit it from time to time to see whether your initial assumptions about rates of return, lifespan, inflation, and expenses are still accurate, and whether your strategy needs to be updated. 


Approaches to Ensure a Sustainable Withdrawal Rate


Conventional wisdom about withdrawal rates

The process of determining an appropriate withdrawal rate continues to evolve. As baby boomers retire and individual savings increasingly represent a larger share of retirement income, more research is being done on how best to calculate withdrawal rates.

A seminal study on withdrawal rates for tax-deferred retirement accounts (William P. Bengen, “Determining Withdrawal Rates Using Historical Data,” Journal of Financial Planning, October 1994), looked at the annual performance of hypothetical portfolios that are continually rebalanced to achieve a 50-50 mix of large-cap (S&P 500 Index) common stocks and intermediate-term Treasury notes. The study took into account the potential impact of major financial events such as the early Depression years, the stock decline of 1937-1941, and the 1973-74 recession. It found that a withdrawal rate of slightly more than four percent would have provided inflation-adjusted income for at least 30 years. More recently, Bengen used similar assumptions to show that a higher initial withdrawal rate–closer to five percent–might be possible during the early, active years of retirement if withdrawals in later years grow more slowly than inflation.

Other studies have shown that broader portfolio diversification and rebalancing strategies can also have a significant impact on initial withdrawal rates. In an October 2004 study (“Decision Rules and Portfolio Management for Retirees: Is the ‘Safe’ Initial Withdrawal Rate Too Safe?,” Journal of Financial Planning), Jonathan Guyton found that adding asset classes, such as international stocks and real estate, helped increase portfolio longevity (although these asset classes have special risks). Another strategy that Guyton used in modeling initial withdrawal rates was to freeze the withdrawal amount during years of poor portfolio performance. By applying so-called decision rules that take into account portfolio performance from year to year, Guyton found it was possible to have “safe” initial withdrawal rates above five percent.

A still more flexible approach to withdrawal rates builds on Guyton’s methodology. William J. Klinger suggests that a withdrawal rate can be fine tuned from year to year using Guyton’s methods, but basing the initial rate on one of three retirement profiles. For example, one person might withdraw uniform inflation-adjusted amounts throughout their retirement; another might choose to spend more money early in retirement and less later; and still another might plan to increase withdrawals with age. This model requires estimating the odds that the portfolio will last throughout retirement. One retiree might be comfortable with a 95 percent chance that his or her strategy will permit the portfolio to last throughout retirement, while another might need assurance that the portfolio has a 99 percent chance of lifetime success. The study (“Using Decision Rules to Create Retirement Withdrawal Profiles,” Journal of Financial Planning, August 2007) suggests that this more complex model might permit a higher initial withdrawal rate, but it also means the annual income provided is likely to vary more over the years.

Don’t forget that all these studies are based on historical data about the performance of various types of investments, and past results don’t guarantee future performance.


How does a sustainable withdrawal rate work?

Perhaps the most well-known approach is to withdraw a specific percentage of your portfolio each year. In order to be sustainable, the percentage must be based on assumptions about the future, such as how long you’ll need your portfolio to last, your rate of return, and other factors. It also must take into account the effect of inflation.

Example(s): John has a $2 million portfolio when he retires. He estimates that withdrawing $80,000 a year (adjusted for inflation) will be adequate to meet his expenses. John’s sustainable withdrawal rate is four percent, and he must make sure that his portfolio is designed so that he can continue to take out four percent (adjusted for inflation) each year.


Other approaches to withdrawal rates


A performance-based withdrawal rate

With this approach, an initial withdrawal rate is established. However, if you prefer flexibility to a fixed rate, you might vary that percentage from year to year, depending on your portfolio’s performance. Each year, you would set a withdrawal percentage, based on the previous year’s performance, that would determine the upcoming year’s withdrawal. In years of poor performance, a portfolio’s return might be lower than your target withdrawal rate. In that case, you would reduce the amount you take out of the portfolio the following year. Conversely, in a year when the portfolio exceeds your expectations and performance is above average, you can withdraw a larger amount.

Example(s): Fred has a $2 million portfolio, and withdraws $80,000 (four percent) at the beginning of his first year of retirement to help pay living expenses. By the end of that year, the remaining portfolio balance has returned six percent, or $115,200–more than the $80,000 he spent on living expenses. For the upcoming year, Fred decides to withdraw five percent of his portfolio, which is now worth $2,035,200 ($2 million – $80,000 + $115,200 = $2,035,200). That will give him $101,760 in income for the year, and leave his portfolio with $1,933,440. However, during December of that second year of retirement, his portfolio experiences a seven percent loss; by the end of the year, the portfolio has been reduced by the $101,760 Fred withdrew at the beginning of the year, plus the seven percent investment loss. Fred’s portfolio is now worth $1,798,099. Fred reduces his withdrawals next year–the third year of his retirement–to ensure that he doesn’t run out of money too soon. (For simplicity’s sake, this hypothetical illustration does not take taxes in account, and assumes all withdrawals are made at the beginning of the year.)

Caution: If you hope to withdraw higher amounts during good years, you must be certain that you’ll be able to reduce your spending appropriately during years of lower returns; otherwise, you could be at greater risk of exhausting your portfolio too quickly. And be sure to take inflation into account. Having other sources of reliable, fixed income could make it easier to cushion potential income fluctuations from a performance-based withdrawal rate, and handle emergencies that require you to spend more than expected.


A withdrawal rate that decreases or increases with age

Some strategies assume that expenses in the later years of retirement will be lower as a retiree becomes less active. They are designed to provide a higher income while a retiree is healthy and able to do more.

Example(s): Bill sets a six percent initial withdrawal rate for his portfolio. However, he anticipates reducing that percentage gradually over time, so that in 20 years, he’ll take only about three percent each year from his portfolio.

Caution: Assuming lower future expenses could have disastrous consequences if those forecasts prove to be wrong–for example, if health care costs increase even more sharply than they have in the past, or if a financial emergency late in life requires unplanned expenditures. Even assuming no future financial emergencies and no unexpected increases in the inflation rate, this strategy would require discipline on a retiree’s part to reduce spending later, which might be difficult for someone accustomed to a higher standard of living.

Other strategies take the opposite approach, and assume that costs such as health care will be higher in the later retirement years. These set an initial withdrawal rate that is deliberately low to give the portfolio more flexibility later. The risk, of course, is that a retiree who dies early will leave a larger portion of his or her retirement savings unused.


Income-only withdrawals vs. income and principal

Many people plan to withdraw only the income from their portfolios, intending not to touch the principal unless absolutely necessary. This is certainly a valid strategy, and clearly enhances a portfolio’s sustainability. However, for most people, it requires a substantial initial amount; if your portfolio can’t produce enough income to meet necessary expenses, an income-only strategy could mean that you might needlessly deprive yourself of enjoying your retirement years as much as you could have done. A sustainable withdrawal rate can balance the need for both immediate and future income by relying heavily on the portfolio’s earnings during the early years of retirement, and gradually increasing use of the principal over time in order to preserve the portfolio’s earning power for as long as possible.

Planning to use both income and principal requires careful attention to all the factors mentioned above. Also, in establishing your strategy, you should consider whether you want to use up all of your retirement savings yourself or plan to leave money to heirs. If you want to ensure that you leave an estate, you will need to adjust your withdrawal rate accordingly.

Your decision about income versus income-plus-principal should balance the need for your portfolio to earn a return high enough to sustain withdrawals with the need for immediate income. That can provide a challenge when it comes to allocating your assets between income-oriented investments, and investments that have the potential for a higher return but involve greater volatility from year to year. You may need to think of your portfolio as different “buckets”–for example, one “bucket” for your short-term living expenses, another bucket that could replenish your expenses bucket as needed, and another bucket invested for the long term.



For retirees or near retirees, ensuring their savings truly lasts a lifetime is of critical importance. Developing a sustainable withdrawal rate, and actively reviewing it on an annual basis, will do a great deal to help retirees overcome the fear and stress of possibly running out of money. If this seems daunting and complex, talk to a financial advisor such as Mackey Advisors.

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