Received a CP11 from the IRS based on the Refundable Child Tax Credit (Panic is setting in)

I've been doing my own taxes since 2006 and not once have I had an issue. I've always used TurboTax too. 

 

My wife and I filed mid-March and noticed it was taking longer than normal to get our return (right around $700). I get the mail today with a notice from the IRS stating that they made a change to my return based on the Refundable Child Tax Credit. We now OWE $2,241!! 

 

Under the payments and credits section, specifically under "Other credit, Form 1040 lines 27a, 28-30, SCH 3 lines 9, 11, 12, 14" they show my credit as $3,000. Correct me if I'm wrong but isn't the child tax credit $3,000/child. I have two between ages 6 and 17. These are the values that TurboTax automatically entered when the info I enter in for my children has us qualify for the tax credit.

 

What am I missing here? We received the advanced Child Tax Credit. Is that what's happening here??