I received a large (>$10k) check unexpectedly in the mail from my company's new 401K provider. We have been with this provider for only part of this year. Logging in to my account I see that this was a withdrawal for "excess contribution" from my account. I don't really see how this is possible as the payroll company always stops the 401k deferral at the appropriate limit, $19,500 for me last year, for example. I have been calling and calling the provide to try to get resolution, and am being told "it is being researched".
Is there any way that this is legitimate, or am I correct in my assumption that this was done in error?