I've read some older dialouge (2007 and earlier) here about the requirements for a separate EIN/TIN for plans, and I've even recently posted on a dissimilar situation from what I'm asking now.
Since the schedule P has been eliminated, I've seen most custodial trust accounts for newer pension/cash balance plans setup with whatever firm (TD, Schwab, etc.) using the ER's EIN to setup the ERISA trust account. The "experts" at these firms also acknowledge that no separate EIN is required. However, when I go to the IRS website, it appears to REQUIRE a separate EIN for the trust.
It appears that there is a wide range of thought on this subject, and even two ERISA attorneys I've spoken with recently have questioned the necessity to establish a separate EIN other than a possibility of income reporting issues. Does anyone have any substantive clarification on this?