Does anything in Form 5500 call for a second organization’s EIN?

Before 2020, partnership A maintained a single-employer individual-account retirement plan for its employees (including those of its partners who are deemed employees).

In 2020, partnership A amended its plan to allow participation by partnership B (for those of its partners who are deemed employees and for employees, if any).

Partnership B is a new-formation startup.  There is no transfer of assets or liabilities from a plan of B into A’s plan.

The two partnerships—while separate artificial persons—are a § 414(m) affiliated service group.

The plan’s governing documents specify partnership A as the plan’s sponsor, administrator, and trustee.  The documents admit partnership B as a participating employer.

Is there anything in Form 5500 that calls for reporting the Employer Identification Number of partnership B?

Since they are considered a single employer filer, I can't think of anything. If it was a multiple employer plan, then there would be.

WCP

Thank you for the quick and good help.

If a practitioner with your great knowledge and abilities can't think of it, it isn't to be found.

1 hour ago, Peter Gulia said:

Thank you for the quick and good help.

If a practitioner with your great knowledge and abilities can't think of it, it isn't to be found.

Well, that's a very nice compliment, but let's don't get carried away here.