When did an irrevocable Trust EIN requirement become effective?
1 attorney answer
I believe EINs were authorized all the way back in 1954 under the Tax Code in place at that time.
The purpose of the EIN is to identify the taxpayer (in your case the irrevocable trust) and to provide a unique number for filing required tax returns (a 1041 tax return would likely be required for the irrevocable trust).
When a trust becomes irrevocable, it stands alone as its own entity, which requires a unique number (an EIN) to be assigned for tax identification and reporting requirements. That's the primary purpose. I'm curious why one was not required for your parents' trust after they passed (assuming they had a trust).