Longevity Risk, the 4 Percent Rule and Safe Withdrawal Rate

Posted on July 6th, 2010 by admin in Quant, Retirement, Safe Withdrawal Rate

Craig Israelsen, Associate Professor, Brigham Young University has said in an interview:

Budgeting skills are as important as what your portfolio is doing—probably, more important really, because budgeting is an everyday issue. If a person can scale back appropriately so that they can actually survive on a 4 percent withdrawal rate, they’re good. Any reasonably designed retirement portfolio will last with a 4 percent withdrawal rate. Eight percent? You’re going to have to get really lucky in your investments.

We love reading his work and he’s a very sharp, knowledgeable finance maven. But his claim about the 4 percent withdrawal rate seems a tad glib–there are many assumptions built-in to this claim that need explanation. Would you really like to bet on such a simple number for your retirement? We think not.

Intuitively, at 4% withdrawal rate,  if your return is 4%/YR and inflation is nil, then in fact you can simply withdraw the gain each year and never deplete the principal. But if, for example, inflation is 2%/YR and your return is 4%/YR, then we can show 4% withdrawal rate would last you 34 years. Not bad. But if your return is 3%/YR and inflation is 4%/YR, then this account will deplete after 22 years if withdrawals are at 4%/YR.  That’s probably a big difference. We show you how to handle all these “What Ifs”.

This post introduces the idea of the Safe Withdrawal Rate (SWR), a concept that has recently captured the attention of many investment advisors and publications. We introduce our own focus on this topic now. We announce two initiatives. First, we published a descriptive piece in Advisor Perspectives, a highly respected and popular website for investment professionals. This piece explains SWR ideas without math for the average investor. Second, we published our full research results in detail here, in our permanent pages (see Investing Tools drop-menu above, or click this link):

Investing Tools> Safe Withdrawal Rate

This page introduces our technical analysis and methodology to determinine your own, personal SWR. Our innovation: we capture each individual’s beliefs about his own future returns and inflation to find the expected value of his SWR, irrespective of market history. Ultimately, your personal beliefs about how future returns and inflation evolve is all that matters for your planning purposes.

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