Is This Income, A Tax Credit, Or What?

This stimulus check is a refundable tax credit for 2020, being paid to you early. You will have to claim in on your 2020 taxes, but there is nothing to pay back... unless:

Your earnings in 2020 exceed the AGI limits
You received an incorrect amount based on household or filing (such as you're now divorced and should have received just a single check, etc.)

So guys for 99.9% here it will not have a negative effect on you and you will not owe anything to IRS next year. Unless of course all the sudden your income in 2020 will increase to over 75k if you are single.