Can I be claimed as a dependent as a 23 year old, at least half time student on 1098-T?

Q. Can I be claimed as a dependent as a 23 year old, at least half time student on 1098-T?

A. Yes, but under a different set of rules, than the ones that apply to a fulltime student under 24.

Yes, there is an income minimum that could  disqualify you. If you made  more than $4300 and were not a full time student, you cannot be anyone's dependent.

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 and full time student status test, a relationship test and a residence test. 

A person can still be a Qualifying relative dependent, if not a Qualifying Child, if he meets the 6 tests for claiming a dependent:

1. Closely Related OR live with the taxpayer ALL year
2. His/her gross taxable income for the year must be less than $4300 (2021).
3. The taxpayer must have provided more than 1/2 his support

In either case:

4. He must be a US citizen or resident of the US, Canada or Mexico
5. He must not file a joint return with his spouse or be claiming a dependent of his own
6. He must not be the qualifying child of another taxpayer

See full dependent rules at: https://turbotax.intuit.com/tax-tools/tax-tips/Family/Rules-for-Claiming-a-Dependent-on-Your-Tax-Return/INF12139.html