Claimed daughter(19) as dependent. She made more than $4050 but I checked she didn't (by mistake). She was a FT student but failed to check box. IRS approve or amendment?

If I am understanding correctly, you correctly claimed your daughter as a dependent by checking some of the wrong boxes in TurboTax? Keep documentation on these issues, but the IRS should approve.

If this is correct, I don't see any reason to amend your return. As long as she did not provide more than half of her own support, you should have treated her as a qualifying child dependent - it sounds like you ended up claiming her as a qualifying relative dependent. However, the result on your return will be the same so no amendment should be needed.

I would file her return and make sure the box that she can be claimed as a dependent is checked. This will make sure there are no issues for her to file her return.

Qualfiying Child Dependent -

1. She is under the age of 19, or a full-time college student under the age of 24
2. She lived with you for more than half of the year
3. She provided less than half of her support. Worksheet 2 in IRS publication 501 can be used to determine whether she provided more than half of her own support.
4. She does not file joint income tax returns.