1. Planning for an average life expectancy. Playing entirely by the law of averages, you have a 50 percent chance of being wrong.
2. Failing to adequately account for inflation. Even at a mild inflation rate, you lose about one-third of your purchasing power every 10 years.
3. Not understanding the “70 1/2 tax trap.” Forced distributions from IRAs and 401(k)s at age 70 1/2 can push retirees into a higher marginal tax bracket and cause up to 85 percent of their Social Security benefit payouts to be taxed.