The choice makes little difference during the first few years, but the longer you live the better off you are with the recalculation method. Under the fixed approach, when you and your spouse reach age 90 you will have withdrawn everything. But if one of you reaches that age your life expectancy will still be five years, meaning that you would only have to withdraw one fifth of what remained in your plan that year if you had opted for the recalculation method. On the other hand, if you choose the recalculation method after one of you dies, you will have to base future distributions on the survivor's life expectancy alone. If one spouse dies at a young age, this choice could accelerate minimum distributions.
Some experts recommend always using the fixed methods.
Others recommend always using the recalculation method unless you or your spouse has a shortened life expectancy for one reason or another. In short, there's no answer that's right for everyone. What you choose may depend on predictions of your longevity and that of your spouse based on your health and the lifespans of other family members. If you designate someone other than your spouse as your beneficiary, you may not elect the recalculation method with respect to his life expectancy, only for your own. What happens to retirement plans after the participant dies depends on whether the decedent had named a designated beneficiary, whether that designated beneficiary is the decedent's spouse, and whether the participant died before or after her required beginning date.