When the grantor of a grantor (living) trust dies, the trust becomes irrevocable. This means that any income earned by the trust after the date of death is reported by the trust on Form 1041. Likely the trust will need to obtain an employer identification number (EIN) but the grantor trust probably was using the grantor’s Social Security number.
A tax year of less than 12 months. May occur with the startup of a business or change in accounting method.