To calculate the estimated required minimum distribution, take the amount of the retirement account balance as of Dec. 1 of the previous year and divide that amount by a life expectancy factor determined by the Internal Revenue Service, explains Vanguard. The life expectancy factor depends on several criteria.
The life expectancy factor depends on who the beneficiary of the account is and the age of the beneficiary, according to the Internal Revenue Service. The IRS provides three tables to assist a person in determining his life expectancy. A person should use the joint and last survivor table if the beneficiary of his account is a spouse who is 10 years younger than he is. The Uniform Lifetime Table is for accounts where the spouse in not the sole beneficiary and is not more than 10 years younger than the account holder. The single expectancy table is for a person who is the beneficiary of his own account. Using one of these charts, a person locates the life expectancy factor that corresponds to his age. The IRS website contains worksheets to help a person calculate his RMD.
If a person possesses more than one retirement plan, he needs to calculate the RMD separately for each account, states Vanguard. The total RMD is the sum of the RMDs from each separate retirement account.