Make sure that you are using the correct life expectancy factor for the 2021 RMD. The current 2021 IRS Pub 590-B has the tables to be used only for 2022 and beyond. Use Table II from the 2020 IRS Pub 590-B: https://www.irs.gov/pub/irs-prior/p590b--2020.pdf
The estate normally passes the income through to the estate beneficiaries on Schedules K-1 (Form 1041) for taxation on the beneficiaries' individual tax returns instead of being taxed at the estate tax rates.
The current IRS Pub 590-B does not incorporate the proposed regulations. They won't update Pub 590-B until the new regulations become final. Beneficiaries generally would not want to wait until year 10 to take the entire balance and spike their income into a higher tax bracket, so taking annual amounts generally makes sense anyway.
