I have received several checks (from securities held in my IRA) sent to me in the name of my IRA for my benefit for similar reasons, so I just endorse the check and send it to the IRA custodian that just adds to the IRA as a miscellaneous transaction. If I cashed the check then that would be a reportable IRA distribution that is difficult to report without a 1099-R that will never occur.
My IRA plan trustee has never has an issue with this so I assume that a 401(k) plan trustee should know how to handle it.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
