over-contributed QNEC

Client has an auto-enrollment 401(k) plan.  They did a QNEC for a group of participants for missed deferral opportunity a few months ago and just realized some of them received an amount that was too high.  All impacted participants are NHCEs.  I'm not finding a correction for this.  Let the participants know of the error and forfeit?

Thanks for your help!

Confirm that the excess doesn't violate the bottom-up restrictions and leave anything that's ok in place.  You can forfeit any excess that doesn't pass the targeted hierarchy.