The specific calendar date by which you must start taking Required Minimum Distributions (RMDs) from your retirement accounts. For most people, this is April 1st of the year following the year you turn 73 (as of 2023, increasing to 75 in 2033). Roth IRAs do not have RBDs during the owner's lifetime, but inherited Roth IRAs and Roth 401(k)s may have different rules.