December 31, 2010 is an important deadline for individuals who inherited an IRA from an IRA owner who died in 2009. Where there are multiple beneficiaries for the IRA, splitting up the account into several accounts no later than December 31, 2010, can yield important tax and other benefits for each beneficiary.

Background. Designating several beneficiaries for an IRA may put the younger one (or ones) at a disadvantage if they want to keep required minimum distributions (RMDs) as small as possible and keep IRA deferrals going for as long as possible. Reason: As a general rule, where there is more than one IRA designated beneficiary, the one with the shortest life expectancy (that is, the oldest one) is treated as the designated beneficiary for determining distributions.

Observation: The oldest-beneficiary rule comes into play for determining RMDs after the IRA owner’s death. Regardless of whether the IRA owner died before or after his required beginning date, if the IRA owner was older than any of the beneficiaries, the remaining IRA balance at the owner’s death is paid out over the remaining life expectancy of the oldest designated beneficiary.

Illustration : Anne designated her son, Seth, and her daughter, Carol, as equal beneficiaries of his IRA. Anne died in 2009 at the age of 74. Seth, age 50 this year, wants to invest the inherited IRA in emerging markets mutual funds. Carol, age 44 this year, wants to invest the inherited IRA in a target-retirement-date mutual fund. If the IRA is left as-is, annual RMDs for both Seth and Carol, which must commence in 2010, are based on Seth’s life expectancy, which is shorter than Carol’s. And they may find it hard to reconcile their differing investment philosophies.

Post-mortem planning solution. The beneficiaries can split up the IRA into separate accounts no later than the end of the year following the year in which the decedent died. Where an IRA is divided into separate accounts (i.e., subaccounts), the RMD rules separately apply to each separate account, effective for years after the year in which the separate accounts were created, or the IRA owner’s date of death, if later.

Thus, in the illustration above, if Seth and Carol direct the IRA trustee to split Anne’s IRA into two separate and equal IRAs no later than December 31, 2010, with each the sole beneficiary of one of the equal IRAs, Seth’s RMD will be based on his table life expectancy, and Carol’s will be based on her life expectancy, which is longer than Seth’s. Seth can invest his half of the inherited IRA in emerging markets mutual funds, and Carol can invest her half in the mutual fund of her choice.

For purposes of the RMD rules, separate accounts in an IRA account are separate portions of the IRA owner’s benefit reflecting the separate interests of the IRA’s beneficiaries as of the date of the IRA owner’s death for which separate accounting is maintained.

For the separate or “subaccount” IRA to be treated as a separate account for RMD purposes, it must be established no later than the last day of the year following the year of the IRA owner’s death. Additionally, a separate accounting must allocate all post-death investment gains and losses for the period before the separate accounts were established on a pro rata basis in a reasonable and consistent manner among the separate accounts. However, once the separate accounts are actually established, separate accounting can provide for separate investments for each separate account under which gains and losses from the investment of the account are only allocated to that account. Alternatively, investment gain or losses can continue to be allocated among the separate accounts on a pro rata basis. A separate accounting must allocate any post-death distribution to the separate account of the beneficiary receiving that distribution.