Based upon my research, distributions to Generation Skipping Trust (GST) from Rev. Trusts (now irrevocable upon 2nd death), must be reported regardless of amount, but can be reported on either 706 or 709 returns.  Deceased died in 2022, but trusts distributions to Part 1 and Part 3 beneficiaries occurred in 2023. Entering on tax year 2023 form 709 return as easier and form 706 isn't available in PTO. Also, GS amount is well below GST Lifetime Exemption threshold, therefore no GST tax due.

Where should the Irrevocable trust EIN be entered? 

Thank you in advance!