A client of mine, we just recently discovered that we had been filing Schedule B for 10 years with an incorrect Plan Number, though EIN was correct. The client prepares their own Form 5500, and so it look like it is only the Schedule B plus PBGC Form 1/Schedule A that had been filed with the incorrect PN. Do we need to file amended Schedule B for 10 years? How about PBGC Form 1/Schedule A?

Hope somebody have had the same experience dealing with the issue.....

Does the client have another active plan? If so, could there be confusion with the filings based on the respective plan numbers?

They do have a 401k plan, but the plan sponsor only has one qualified db plan for which a Schedule B (and PBGC Form 1 and Schedule A) is required.

Personally, I would correct it on a prospective basis...