Certain retirement accounts are subject to required minimum distribution rules upon reaching a certain age, typically 70 1/2. At this point, the account participant is required to withdraw a certain amount from the account(s) each year, and these withdrawals are usually subjected to income tax. The participant may withdrawal more than the required amount and still be in compliance with the rule. The rules apply to IRA accounts, SEP-IRA accounts, SIMPLE IRA accounts, 401K plans, 403B plans, 457 plans, and other defined contribution plans. Note that ROTH IRAs are not subject to the rule in most cases.
The amount of the required minimum distribution is based upon age and marital status, and is determined based upon mortality tables. The details of the calculation will not be covered here, however most account custodians will calculate the required minimum distribution for the account owner.