Thank you so much for the info and I'll absolutely look into signing up for that newsletter! 

The icky thing is that my client just received his second W-2 last Friday (I know...VERY late) and we've been working hard to expedite the issue with the retirement plan/HR person. 

So...hypothetically...if logistically the excess deferrals and earnings can't get to him by April 15th (tomorrow), are they considered distributed in 2021, along with the earnings to correct the issue that way?  Or is he just haunted by this until retirement age?  What does that situation look like where we've started the corrective process but he doesn't get the check until maybe next week, after the deadline?  (Going through the interactive tool, it just says you're taxed in the year the excess contributions were made and when they get distributed.)