My reply was with respect to the date mentioned in the original poster's question. vikingsfan6218, since your case involves the decedent dying in 2019, the deadline for splitting the accounts to allow each designated beneficiary to use their own age for determining RMDs is December 31, 2020.
Because distributions made after the death of the IRA participant are taxable to the beneficiary receiving the distribution, custodians generally want you to establish the separate inherited IRAs before any beneficiary takes a distribution. This makes the preparation of a Form 1099-R by the custodian much more straightforward since the separate inherited IRA account will have all of the necessary information needed by the custodian to provide the beneficiary with the form. The custodian will also generally require splitting the IRA before making any distributions to beneficiaries to avoid any complications in determining the beneficiaries' respective shares. Splitting the IRA has no effect on the year-of-death RMD being able to be satisfied by the beneficiaries in any combination.
Making sure that the year-of-death RMD is fully satisfied will require coordination among the beneficiaries. If coordination is not possible to ensure that the year-of-death RMD has been satisfied (because, say, one of the beneficiaries is uncooperative), it would probably be wise for an individual beneficiary take a distribution of the year-of-death RMD in proportion to their respective share of the inherited IRA.
If the 2019 RMD is not completed before the end of 2019, the beneficiaries will need to file 2019 Form 5329 requesting waiver of the 50% excess accumulation penalty and to explain how the 2019 RMD was eventually satisfied. With two months remaining before the end of 2019, it should be possible to complete the distribution before the end or 2019 and avoid any need to file Form 5329.
