The required minimum distribution, or RMD, rules force tens of millions of retirees to take money out of their tax-deferred retirement accounts each year. The reason for the forced disbursement is simple: The government figures it's waited long enough for the taxes on that sheltered cash. The rule to force withdrawals, developed more than 20 years ago, also was intended to make sure that tax-deferred retirement accounts are used for their intended purpose and not by those who would accumulate money tax-free to pass on to heirs.