Don't take a lump sum distribution.
When you are subject to the 10-year liquidation rule for newly inherited IRAs,
to spread the tax impact most evenly over the ten years,
your divisor should be : 10 - N where N is the number of annual distributions you already took.
In other words, with four years gone by, you want to take out one sixth of the IRA,
If you are a young beneficiary or even a senior, this rule would generate much larger RMD than the RMD based on Pub590B formulas.
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Be aware that the proposed regulations from the IRS dictate that if the decedent died after their required beginning date for RMDs, both annual RMDs based on life expectancy and full distribution by the end of the 10th year following the year of death are required (which is different from what was published in the final version of 2021 IRS Pub 590-B). Annual distributions are not required only if the decedent died before the required beginning date for RMDs.
