William Bernstein and Safe Withdrawal Rates

A recurring theme in investing is that you start out learning the simple basics, then you feel like you can optimize things and spend a lot of effort trying to do so, and eventually you realize that simple is probably just fine. No matter how closely you mine the past, you can’t predict the future. As the Buffett quote goes, “If past history was all there was to the game, the richest people would be librarians.” That’s what came to mind when I read William Bernstein on safe withdrawal rates in retirement:

Even the most sophisticated retirement projections contain so much uncertainty that the entire process can be summarized as follows: Below the age of 65, a 2% spending rate is bulletproof, 3% is probably safe, and 4% is taking chances. Above 5%, you’re taking an increasingly serious risk of dying poor. (For each five years above 65, add perhaps half of a percentage point to those numbers.)

Source: The Ages of the Investor: A Critical Look at Life-cycle Investing.

Something to keep in mind when you become obsessed about getting from a 98% success rate to a 99% success rate on a simple retirement calculator from Vanguard or a fancy one like FIRECalc. (Not that I’ve done that, ever, of course…)