Distributions Resulting from Fraud - Can a DB Plan Recover Amounts Paid to IRS?

[lrc14]

The administrator of a DB plan recently learned that an individual it was making survivor payments to died more than 15 years ago. The plan had been making survivor annuity payments by direct deposit into a bank account belonging to the now-deceased survivor and her son. The son is believed to be the subject of a pending Social Security fraud investigation. Obviously, the plan will be pursuing recovery against the son of amounts distributed since the individual's death; however, does the plan have any recourse against the IRS to recover the amounts withheld from the distributions and sent to the IRS? Assume for purposes of this question that neither the son nor anyone else filed any (fraudulent) returns on behalf of the deceased individual - in other words, the IRS never paid that money back as a tax refund. We do not believe filing corrected 1099s is appropriate, since distributions were actually made.