Recently we were involved in a discussion regarding how to fix a plan that had made non safe harbor formula contributions to a profit sharing plan. It was discussed that a corrective amendment could be prepared for 401(a)(4) testing for all three years (2001, 2002, 2003) as long as the amendment was signed and dated before Sept. 2004. Does this sound correct to anyone? Thanks

doesn't sound correct.
corrective amendment must be made by 9 1/2 months of plan year end.
so it could be done for 2003, but the prior years are another story

Actually Tom, eliano may be right or almost right if his plan only recently was issued a Favorable Determination Letter. You have extended time if an FDL is pending, I believe 90 days following issuance of an FDL. See 1.401(a)-(11)-(g)(3)(iv)(B).

Then you need to follow the additional cite of 601.201(o), wherever that is. I did find it once and it was worth the effort.

I only learned of this last year myself. I don't think it is commonly known.