Once you reach age 70½, you are required by the IRS to take annual Required Minimum Distributions (RMDs) from your retirement accounts. You need to calculate your RMD for each IRA separately, but you have the flexibility take your total RMD amount from either a single IRA or a combination of IRAs. However, RMDs from Qualified Retirement Plans or Inherited IRAs must also be calculated separately, and can only be taken from their respective accounts. You do not need to take RMDs for Roth IRAs.
