I understand that 401(k)s have a mandatory withdrawal that can be triggered at some point.

What triggers a 401(k) mandatory withdrawal, and how is the amount of the withdrawal calculated?

1 Answer 1


The mandatory withdrawal period starts on April 1st of the year after:

  • The calendar year in which you reach age 70½.
  • The calendar year in which you retire.

Whichever comes later.

The minimum amount of the withdrawal is based on actuarial tables designed to ensure that the entire amount is distributed over your lifetime or the combined lifetime of you and your spouse/beneficiary. There is a calculator here that you can use to calculate what that amount would be. Or if you prefer to see the tables, the whole thing is explained in detail in IRS Publication 590

  • 2
    Perhaps the statements above were correct according to 2010 law, but I believe that under current law, mandatory withdrawals start in the year in which the owner turns 70½, and not in the year after The first year withdrawal can be postponed till April 1 of the following year, but then, in that following year, two withdrawals must be made: the first by April 1 (takes care of the delayed withdrawal for the previous year), and the second by December 31 (for the year in which the owner is 71½). This increases the taxable income for that second year. Jan 9, 2016 at 18:20

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