Sorry for your loss. The estate’s tax year begins on the date on which the deceased person died. You, as executor, can select any year end as long as it not more than 12 months and ends on the last day of the month preceding the month of death.
so if the death occurred in March 2020 you can have any year-end up until 2/28/2021. the next year would start on 3/1/2021. a short year return can be filed by using the 2020 tax forms - indicate the beginning and ending dates when asked.
the question I can't answer because i know nothing about the documents that govern the estate is whether the trust pays the taxes on the gain or the gain is distributed to the beneficiaries who pay the tax. generally, if this is the final return the gain would be distributed to the beneficiaries.
