The RMD changes in the SECURE Act apply with regard to decedents dying after 2019. These changes do not apply in this case.
Because mom left the IRA to her estate, there was no designated beneficiary; a designated beneficiary can only be an individual. (The beneficiaries of the estate do not constitute beneficiaries of the IRA, except in some cases where the decedent's spouse is the sole beneficiary of the estate). Because the beneficiary of the IRA was not an individual, if the mom died before her Required Beginning Date for RMDs, distributions must be made under the 5-year rule. If mom died after her RBD for RMDs, RMDs are based on mom's remaining life-expectancy based on her age in 2019. Even if mom had died in 2020 or later, there are no changes in the SECURE Act that apply when the beneficiary is not an individual.
Only trusts, not estates, can be qualified for look-though treatment for determining RMDs.
Since the estate was a beneficiary (in this case apparently the only beneficiary) and is not removable as a beneficiary, the September 30 deadline does not apply. The rules for the IRA being inherited by a non-individual apply.
