Retirement Planning: Definition of Required Minimum Distributions

Required minimum distributions (RMDs) are amounts which must be distributed from your qualified retirement plans, such as 401(k)s and IRAs every year. These precise amounts are based on the balances in your accounts as well as your age. Roth IRAs do not face any required minimum distributions, meaning you can have a sizable account balance at death even if you live well into your nineties. The penalty for not honoring your RMD obligation is 50% of the shortfall. As such, you will always choose to withdraw the RMD. If you're not yet 70 ½ years old, you don't have to worry about RMDs, but make sure your parents are taking care of this responsibility.

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How to Retire Happy, Wild, and Free: Retirement Wisdom That You Won't Get from Your Financial Advisor
The Bogleheads' Guide to Retirement Planning
The Complete Idiot's Guide to Retirement Planning
Save Your Retirement: What to Do If You Haven't Saved Enough or If Your Investments Were Devastated by the Market Meltdown