At age 18, your mom can claim you as her dependent. If you can be claimed as a dependent on your parents’ return, you can still file your own return so that you can receive a refund of taxes withheld. (You will not get back anything for Social Security or Medicare withheld.) You will not get the $4050 personal exemption. Be sure that on your own return you say that you can be claimed as a dependent on someone else’s return.