It is not income and not taxable. You are getting credit for the additional 1500. But Turbo Tax started out giving you the full amount. Then you enter what you already received so it subtracts it. Check 1040 lines 19 and 28 and schedule 8812.
Before filing you can preview the 1040 or print the whole return
https://ttlc.intuit.com/community/accessing/help/how-do-i-preview-my-turbotax-online-return-before-f...
