There is no minimum age for filing a federal income tax return. If you are under age 18 you may have to file a tax return, depending on your income for the year. Or it may be to your advantage to file a return to obtain a refund for the tax withheld from your paycheck. If state income taxes are withheld from your pay, you should also file a state income tax return to obtain a refund.
The filing requirements generally are based on your income and filing status. For example, for 2011 if you are single and had gross income of $9,500 or more, you would have to file a federal income tax return. Gross income would include any earnings from work, investment income such as interest and dividends, and any other taxable income.
If you can be claimed as a dependent on your parents’ or someone else’s tax return the filing requirements are different. According to the IRS, in this case you would have to file a return (for 2011) if you have earned income of more than $5,800, unearned income of more than $950, or if your gross income is more than the larger of $950 or your earned income up to $5,500 plus $300. For example, if you had wages of $5,400 and investment income of $500, both individual amounts would be below the filing limits, but since the total is more than $5,800 you would have to file.
If you can be claimed as a dependent and are married, the same filing requirements apply. But, if you are married and your spouse files a separate return and itemizes deductions, you would have to file a return if you had gross income of at least $5.
If you are self-employed and had net earnings of at least $400 you would have to file a federal tax return in order to pay the self-employment tax. This is the equivalent of the social security and Medicare tax withheld from salaries and wages. By filing and paying this tax you are accumulating credits to qualify for social security when you retire. The self-employment tax is reported on Schedule SE.
The filing requirements may change from year to year. You can find charts with the filing requirements in various different IRS publications, such as Publication 17, Your Federal Income Tax; Publication 501, Exemptions, Standard Deduction, and Filing Information; or in the instructions for Form 1040 or Form 1040A. These are all available on the IRS website.
If your parents or someone else can claim you as a dependent on their tax return, you could not claim an exemption for yourself on your own tax return. According to the IRS, this is true even if your parents or other person does not actually claim the exemption for you as a dependent.
Also, if you can be claimed as a dependent by someone else, you cannot claim anyone else as a dependent. For example, if you have a child and your parents can claim you as a dependent, you cannot claim a dependent exemption for your child. But your parents may be able to claim your child as a dependent, if the qualifying tests are met.
If you can be claimed as a dependent, the standard deduction you can claim is limited. According to the IRS, for 2011 you could claim the greater of $950 or your earned income for the year plus $300, but not more than the regular standard deduction of $5,800 for a single taxpayer.
Publication 17, Your Federal Income Tax, IRS
Publication 501, Exemptions, Standard Deduction, and Filing Information, IRS
Publication 929, Tax Rules for Children and Dependents, IRS
Schedule SE, Self-Employment Tax, IRS