The waiver is only for beneficiary RMDs under the 10-year rule. There is no general waiver of the penalty for failing to complete the outstanding portion of the decedent's 2024 RMD. However, as KrisD15 said, you (and any other beneficiaries of this IRA) have until December 31, 2025 to complete the decedent's 2024 RMD. This distribution must be completed along with your own 2025 beneficiary RMD and it will all be reportable on your 2025 tax return.
Due to the automatic extension of the deadline to the end of the year following the year of death, there is no need to file a 2024 Form 5329 requesting a waiver of the excess-accumulation penalty as long as the decedent's 2024 RMD is completed by the end of 2025.
