Per IRS Publication 590-B Distributions from Individual Retirement Arrangements (IRAs), page 8:
Figure your required minimum distribution for each year by dividing the IRA account balance (defined next) as of the close of business on December 31 of the preceding year by the applicable distribution period or life expectancy. Tables showing distribution periods and life expectancies are found in Appendix B and are discussed later.
IRA account balance. The IRA account balance is the amount in the IRA at the end of the year preceding the year for which the required minimum distribution is being figured.
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Reporting the tax. Use Form 5329 to report the tax on excess accumulations. See the discussion of Form 5329, later, under Reporting Additional Taxes for more information on filing the form.
To report excess accumulation in the TaxAct program:
To request a waiver of tax on your excess accumulation in qualified retirement plans:
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