Mandatory distribution refers to the minimum amount an individual must withdraw from certain types of tax-advantaged retirement accounts each year in order to avoid tax penalties. Mandatory distributions go into effect in the year an individual turns 70 ½ years old. The Internal Revenue Service’s official name for mandatory distributions is required minimum distributions, or RMDs.

Mandatory distributions apply to traditional individual retirement accounts, 401(k)s, 403(b)s, 457(b)s, SEPs, SARSEPs, SIMPLE IRAs and Roth 401(k)s. They do not apply to Roth IRAs during the owner’s lifetime.

Once the age trigger is reached, the person must take mandatory distributions by December 31 each year. Otherwise, the IRS imposes stiff penalties: a tax of 50% on the amount that should have been withdrawn.

Exceeding the mandatory distribution is allowed. However, excess withdrawals do not reduce required minimum distributions in future years.

Mandatory distributions are taxed at an individual’s current marginal tax rate.

Of note, in the very first year of mandatory distributions, some retirees end up taking two years’ worth of distributions. This is because the IRS allows retirees to delay the first distribution until April 1 of the following year. This allows tax-advantaged investment returns to build up for a longer period of time.  

The rules for mandatory distributions change if the retirement account in question is inherited. Instead of waiting until age 70 ½,  beneficiaries have two options. They can withdraw the entire account balance within five years of the owner’s death, or the take mandatory distributions over their entire lifetime, as long as they begin within one year of the owner’s death.

Mandatory distribution amounts are based on the account balance and the account holder’s life expectancy, as determined by IRS tables. IRA custodians and plan administrators usually calculate RMDs for account holders, though technically it is the account holder’s responsibility to determine the correct minimum distribution amount.

Workers that do not own more than 5% of the company for which they work have the OK from the IRS to postpone taking mandatory distributions from retirement accounts associated with that job until April 1 of the year after they retire.

How to Calculate a Mandatory Distribution

The amount of a mandatory distributions is calculated separately for each account. For an IRA, for example, take the account balance as of the previous December 31, then divide this by a so-called life-expectancy factor. The IRS includes these factors in Publication 590-B, Distributions from Individual Retirement Arrangements (IRAs).

There are three different tables in the publication, based on different life situations. Choose the Joint and Last Survivor Table if a spouse is the sole account beneficiary, and this beneficiary is more than 10 years younger than the other marriage partner. Choose the Uniform Lifeline Table if you have a spouse, but one that does not fit the definition given in the Joint and Last Survivor Table. Finally choose the Single Life Expectancy Table if you are the beneficiary of an account or an inherited IRA.

Amy Fontinelle is a writer, editor, and personal finance expert. Her clients include personal finance websites, financial institutions, public policy organizations, academic journals and professional economists. She has written hundreds of articles on budgeting, credit cards, mortgages, real estate, investing and other topics. In addition to Investopedia, her articles have been featured on the homepage of Yahoo! and on Yahoo! Finance, Forbes.com, SFGate.com, Bankrate and other websites. 

In addition to her personal finance articles, Amy writes business-to-business copy and composes ghostwritten and content marketing pieces. She polishes articles and papers written by economists, consultants and other professionals who need to communicate clearly and compellingly through their writing. She has also defined hundreds of financial terms for Investopedia's online dictionary and written in-depth tutorials on budgeting, banking, investing and home buying. Learn more about Amy at www.AmyFontinelle.com.

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