Safe withdrawal rate accounts for inflation and taxation related effects, too. If you have $1M returning 9% per year, and withdraw $90k/year, you're either goi

Safe withdrawal rate accounts for inflation and taxation related effects, too. If you have $1M returning 9% per year, and withdraw $90k/year, you're either going to be spending less in real money in each year -- as inflation reduces the value of $90k and the amount of tax increases each year-- or you're going to be withdrawing more each year and depleting the principal.