A Required Minimum Distribution is exactly what it sounds like: a minimum amount the IRS requires you to withdraw from certain retirement accounts every year, once you reach a specific age. The rule exists to stop tax-advantaged accounts from being used as permanent tax shelters, or purely as a way to pass wealth to heirs without ever being taxed. * RMD rules apply broadly across employer-sponsored plans — 401(k)s, 403(b)s, 457(b)s, and profit-sharing plans — as well as Traditional IRAs and IRA-based plans like SEP and SIMPLE IRAs. Roth IRAs are the notable exception: they have no RMD requirement at all during the original account owner's lifetime, one of their biggest structural advantages over Traditional accounts. * The amount isn't arbitrary or something you calculate on your own from scratch. Each year's RMD is calculated by taking the account's balance as of the prior December 31 and dividing it by a life expectancy factor published in IRS Publication 590-B — as you get older, that factor shrinks, which pushes your required withdrawal percentage up each year. * Deadlines matter here, and missing one is expensive. After your very first RMD year, you generally must withdraw the required amount by December 31 every year. Fail to withdraw enough, and the IRS can charge a 25% excise tax on the shortfall — though that penalty drops to 10% if you catch and correct the mistake within two years. * Because the calculation depends on account balances and IRS life expectancy tables that update periodically, most people rely on their brokerage or plan administrator to calculate the exact required amount each year rather than doing the math independently.