Our daughter is in college working on a masters and lives with us. We take her as a dependent for Healthcare insurance, and we pay almost all of her expenses. She worked part time and earned an adjust gross income of $6712.
Turbo Tax shows that her income does not qualify as a dependent. How does that impact Healthcare insurance for 2019? She is eligible to be covered this year? It is hard to believe that she is not considered a dependent at that income level.
If your daughter is older than 23 years old, if she didn't earn less than $4150 in 2018, she doesn't qualify as your dependent, even if she didn't support herself and even if she is a college student.
She may still qualify to be on your health plan, or she may be able to obtain her own coverage through HealthCare.Gov, or through your state agency.
and to add to the response, the rules are simply different.
The Health Care laws permit children to remain on your plan until they attain the age of 26 while the tax credit rules change at various ages
Per the link below from TT, if the child is over 23 on 12/31/18 then the income test come into play. The fact that TT asked you the income question would suggest she is over 23.
The income question is not asked if the child is under 24 as that doesn't determine your child's eligibility for either the $2000 child tax credit (under 17) or the $500 other dependent credit (under 24)