"I'm trying to figure out the rules when a plan is terminated just before the employer is acquired, and its employees are thereafter covered by the acquirer's plan.
"Let's call the acquired company A and its plan, Plan A. The acquiring company's plan is Plan B. The IRS site says that the 415 limit is prorated for a terminating plan, but not in the case of an individual who joins a plan late in the year.
And of course, plans of a single employer are combined.
"In this case, presumably Plan A must apply a prorated 415 limit to contributions made before its termination. But because the employees of A have been employed by the same entity all year, and Plan B did not have a short plan year, presumably Plan B must combine its benefits with those of Plan A in calculating the 415 limits for Plan B.
"But does the reverse
apply? Must Plan A combine its benefits with those of Plan B in calculating the 415 limits for Plan A? Common sense would seem to say no. Plan A had a short plan year, and no contributions were made to Plan B on behalf of A employees during that short plan year. But I haven't found authority directly on point."