An estate can use a calendar tax year or a fiscal tax year. A fiscal tax year is one that ends on the last day of any month other than December. The estate can even file a return for a short tax year if the end date is less than 12 months after the date of death. A fiscal-year filing would likely have to be done before the Form 1099-R is issued near the end of January 2026, so you would have to prepare the return just using the transaction information.
Unless the funds are needed by the estate to pay an estate income tax liability (which would be unusual if the income is passed through to estate beneficiaries on Schedules K-1), make sure to have no taxes withheld from an IRA distribution paid to the estate. Credit for such tax withholding cannot be passed through to estate beneficiaries.
