80 Ill. Adm. Code 2700.870
Mistaken Contributions
Section 2700.870 Mistaken Contributions
If any contribution (or any portion of a contribution) is
made to the Plan by a good faith mistake of fact, then, within one year after
the payment of the contribution and upon receipt in good order of a proper
request approved by the Department, the amount of the mistaken contribution
(adjusted for any income or loss in value, if any, resulting from the good
faith mistake) shall be returned directly to the Participant or, to the extent
required by the Department, to the Employer, who will then return the funds to
the Participant.