The IRS site says the 3rd economic impact payment will NOT reduce my tax return or increase what I owe. Without entering, I get a rebate. With it I owe. Is this accurate

[xmasbaby0]

No but you are misinterpreting the way the software handles the EIP payment.   The software started out by giving you the 3rd EIP payment.   When you entered the amount you already received, the software reconciled it and took it away from that big refund you were seeing in the "refund monitor."    If you already received the 3rd EIP then you should NOT have an amount on line 30 of your Form 1040.   You cannot get it twice.   If you got that payment and it shows up again on line 30, your refund will be delayed for months.

That “refund monitor” should not be taken seriously until every last morsel of your data has been entered.

PREVIEW 1040

https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing

Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.

[DoninGA]

Yes, it is.  The program automatically enters the 2021 Recovery Rebate Credit as NOT received until you enter the amount you have actually received.  Once you have reported the credit received the program removes the amount from the Form 1040 Line 30.