You can't call the IRS to change the dependency claimed on a tax return that has already been filed. You would have to prepare, print and mail an amended return form 1040X to change it. If you meet the requirements to be claimed as a dependent by someone else, you must check the box that you can be claimed whether anyone else actually claims you or not. If you don't meet the requirements, you should not check the box that you can be claimed by someone. Here are the requirements from the viewpoint of someone who could claim you:
1. The child must be your son, daughter, stepchild, foster chld, brother, sister, half brother, half sister, stepbrother, stepsister, or a descendant of any of them.
2. The child must be (a) under age 19 at the end of the year, (b) under age 24 at the end of the year and a full-time student, or (c) any age and permanently and totally disabled.
3. The child must have lived with you for more than half of the year. Temporary absences while away at college are considered living with you.
4. The child must not have provided more than half of his or her own support for the year.
5. If the child meets the rules to be a qualifying child of more than one person, you must be the person entitled to claim the child as a qualifying child.
6. The child must be a U.S. citizen or U.S., Canada or Mexico resident for some portion of the year.
7. The child must be younger than you (or your spouse, if filing jointly) unless disabled.
