Please read the following information related to your tax situation. You may need to provide additional information to receive your full refund.
What to do next? I have not receive any letter. (as of the moment)
Wait for the IRS to send you a letter requesting information.
Do they always send a letter? Before I saw this today, it showed me a status a week ago, and it changed into this notice.
Here is an FAQ about handling identity verification requests from the IRS.
If you have not received a letter yet, you will be.