Thank you for your response. You are correct with the trustee notification question. As I looked further within the details provided; although the taxpayer passed in January, application for estate EIN was not completed until August 2021. In addition, some additional information provided with trustee annual year ending trust statement (TY21) indicated that updated beneficiary information was not signed until January 2022 (possibly also submitted to the bank/trustee around that time). To revise my previous answer, this appears that the trustee was notified but notified very late as they were wrapping up the 2021 Tax year and issued K-1 based on best estimate of allocation (to social).