Thanks everyone for your response to my last question, as they prompted me to do more research (a lot :). The trust I am doing is an intentionally defective irrevocable grantor trust. For initial years grantor used option 1 for filing. I will be filing 2 1041s. The 1st one will be final short year grantor trust Pursuant to section 1.671-4 (g), and the 2nd one (after grantor passed) will be a irrevocable complex trust. My question is, do I use same EIN on both 1041s. I am going to mail in the grantor trust, and efile the other one. Thanks