Why did adding my stimulus checks info change my return from getting a refund to owing?

[xmasbaby0]

You might have become confused by the flow of information in the software.   That "refund monitor" on your screen displays a "refund" amount that includes the stimulus money. as part of your 2020 refund.  The software starts off by giving you the stimulus money.   But later when you enter the amount of stimulus you really received already, it removes the stimulus already given to you.   And it looks to you like you "lost" your refund,   But ---you do not get the same stimulus money twice--that is why it came out.

Look on line 30 of your Form 1040 for your recovery rebate amount.

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.

[VolvoGirl]

You are not paying tax on them and it is not deducting it from your refund or increasing the tax due.  Turbo Tax started out by assuming you didn't get it and  giving you credit for the whole amount so your refund was too high to begin with.  Then when you entered what you already got the starting refund was reduced or the tax due increased to your real actual refund.  Otherwise you would be getting the Stimulus amount again on your tax return.

Look at your return.  The Stimulus payments do not show up anywhere as taxable income so you are not being taxed on it.  And it's not being subtracted anywhere.