Urban legends are seldom-examined stories that circulate as fact. In reality, they are untrue. The sewers of New York are not filled with baby alligators. A frog will jump out of a pot of water that is put on a stove.
The most common urban legend in personal finance is a rule of thumb: the retirement income replacement rate. It says that most people will need 70 percent to 85 percent of the income they earn immediately before retirement when they retire. So if you are earning $50,000 at age 65, you'll need, say, $40,000 in your first year of retirement.
What if you have less? The rule says your standard of living will decline. Prepare to buy a copy of the "Cat Food Diet Cookbook," large-print edition.
This is nonsense. In fact, if you are married, had and educated children, financed the purchase of a home, or paid off student loans, odds are the 70 percent to 85 percent rule doesn't apply to you.
One immediate consequence of having a lower replacement rate is that the amount of money we need to add to Social Security benefits to sustain our standard of living in retirement is smaller. That, in turn, means our nest egg can be smaller. That's fortunate, because most people have smaller nest eggs than they are told they should have.
The fundamental problem with the retirement income replacement rate idea is that it uses income immediately before retirement to measure our needs. It ignores our standard of living during the 40 or 45 preceding years. Basically, it ignores our entire adult lives.
It ignores all the decisions we make that reduce our standard of living when younger. It ignores getting married, buying a house, having children, and educating them. It ignores mortgages that have been paid off, tuition checks that have been cashed, and special help to ailing parents. It ignores the major realities of daily living.
I think you'll agree that's a pretty major omission.
Indeed, I can think of only one person in all of literature for whom the retirement income replacement rate might be a meaningful figure -- John Marcher, the central character in Henry James's "The Beast in the Jungle." His singular distinction as a human being is that nothing at all happened in his entire life -- so his spending would have been quite regular.
Here are five reasons the conventionally used replacement rate is misleading and generally wrong:
If you're thinking, "Wow, I'm off the hook for saving," forget about it. You'll still need to save -- but it may not be a "Mission Impossible."
Scott Burns is a syndicated columnist. He can be reached at scott@scottburns.com. ![]()


