22/full time student. Earned more than 4400. Turbotax doc states < 4400 for the dependent tax credit, however TurboTax includes the $500 credit.

If you are a full time student and under the age of 24 and being claimed as a dependent on your parent's tax return you are eligible for the Other Dependent tax credit of $500 on their tax return.  Your income is not a factor under the Qualifying Child rules, only if you provided over one-half of your own support.

The $4400 income rule doesn't apply.

There are two types of dependents, "Qualifying Children"(QC) and Other ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, student status, a relationship test and residence test.

A child of a taxpayer can still be a “Qualifying Child” (QC) dependent, regardless of his/her income, if:

1. He is under age 19, or under 24 if a full time student for at least 5 months of the year, or is totally & permanently disabled
2. He did not provide more than 1/2 his own support. Scholarships are excluded from the support calculation
3. He lived with the parent (including temporary absences such as away at school) for more than half the year

So, it doesn't matter how much he earned. What matters is how much he spent on support. Money he put into savings does not count as support he spent on himself.

The $4400 income rule is for Qualifying Relatives.