1. General Rule
As a general rule, the account balance used for calculating required minimum distributions (RMDs) is the prior year-end account balance, with no adjustments. For example, if you are calculating an RMD for 2017 you would use the 2016 year-end account balance. If you are calculating a missed RMD for 2014, you would use the 2013 year-end account balance. If you have your first RMD due for 2017 and you take that RMD in March of 2018, you still use the 2016 year-end account balance. As usual with retirement distribution rules, there are some exceptions to the general rule.