I am 24 years old and my parents claimed me as thier dependent on taxes and added me to thier health insurance through covered california with tax credit premiums. I have filed my taxes and somehow I owe $4000 for insurance I never used. Is there anything I can do?
If you were your parents dependent, then you should not have had to enter anything about Health Insurance on your return. Your parents would answer the health insurance on their return.
May I assume that your parents received a 1095-A from Covered California, and that your name is on this form?
If so, you have to file form 8962 to reconcile the amount of premium tax credit that you should have received with what you actually received on this marketplace (Obamacare) policy. You need to get a copy of your parents' 1095-A since I don't believe that Covered California would have sent you one (if your parents told CC that they would be taking you as a dependent).
However, as a dependent, your parents normally would have taken care of the entire reconciliation, and your allocation percentage on form 8962 should have been zero.
See this discussion (especially in the comments) by TaxGuyBill in which he discusses how you do this and the situations in which sometimes the child should take the allocation instead of the parents.
There are two ways to owe money here: (1) you have to pay the individual responsibility payment for not having health insurance (this shouldn't be the case - you did tell TurboTax that you had insurance all year, didn't you?), and (2) you end up owing the IRS for premium tax credit because you were advanced too much credit during the year - this is more likely the case.
Note that you have to coordinate your 1095-A filing with your parents'. That is, if you take 0% of the 1095-A allocation, then your parents have to take 100%, or the IRS will notice.