I'm in the middle of Tax Filing with TurboTax Premier 2021. My wife and I received IRS Form 6419 (advance Child Tax Credit Payments) with $900 each, total $1,800, which is correct. When I type $900 each, $1,800 is getting added to what I owe for Federal Tax Due. Is this normal? My understanding is we are still eligible for $200 Credit since we received $1,800 already, and that $200 Credit is clearly shown in the Overall Deductions & Credits page. But why that $1,800 is going against my Federal Tax Due? Am I missing something?
Yes, it's normal. What you're missing is that when you started your tax return TurboTax assumed that you did not receive any advance payments, so it gave you the full $2,000 credit, and calculated your tax on that basis. When you told it that you got $1,800 of the credit in advance, it reduced the credit to $200 instead of $2,000 and recalculated your tax, so your tax went up by $1,800.
The little box that shows your refund or tax due while you are working on your tax return is really not meaningful until you have entered everything.