Calculating the amount you must withdraw each year (your required minimum distribution) is much easier now than it used to be. Each year, you divide the year-end value of your account by a life expectancy divisor from the Uniform Lifetime Table (provided by the IRS). The result is the minimum you must withdraw for that year. You can always take out more.
For example, the divisor at age 70 is 27.4. If your year-end account balance is $100,000, you divide $100,000 by 27.4, making your first required minimum distribution $3,650. Each year the divisor is smaller, but it never goes to zero. Even at age 115 and older, the divisor is 1.9. “To recalculate or not recalculate” is no longer an issue. Everyone now gets the benefit of recalculating his/her expectancy.