They can't even wait til April 16?

This has to be a scam.  

It looks real. Just incompetent.

I once had an IRS letter saying they couldn't process my 1045 (NOL carryback) claim because it wasn't received by 12/31/xx. The letter was dated 11/15/xx and started out with we received your Form 1045 on 10/2/xx.

If is isn't a scam..... OMG, what are we in for  ?!@!?? 

Both as taxpayers  AND  tax preparers.

From what I found from google search: "IRS uses letter 112C to request that you file your return because they are holding money in your account." I do not know if this statement is accurate or not, it is just what I found.

@BobKamman     how did you respond?

Look at the bright side.  At least they must finally be caught up from the backlog that hit them in 2020.

@PATAX  Yes, there is an ES credit on the 2023 account, from a credit-elect on the 2022 return.  This was sent to an elderly couple; one spouse died in early January, so I suspect someone at IRS must have hit the wrong key and meant to send out some sort of condolence letter (although I have never seen one of those from IRS).  It starts out, "we also have no record. . ."  Why the "also"?  No other notice has been received.  

@dkh I haven't responded yet. This was just brought to me yesterday.  I'm waiting to see if they sent the same nonsense to 50,000 other taxpayers, and will issue a Fuggedaboudit notice.  

It's starts with "We also" so it's like Paul Harvey would say: the rest of the story. There's a prequel somewhere.