Your age does not exempt you from having to file a federal tax return at the end of the year. If you meet the income requirements for filing a tax return, you must file and pay taxes.
If you are single and not listed and a dependent on another person's tax return, the minimums for filing a federal tax return are higher. If you are younger than 65, you must file a return if your taxable income exceeds $9,350. If you are older than 65, you must file if your taxable income is over $10,750.
Heads of Household
To file as a head of household, you must have at least one dependent and not be married. If you use this filing status, you must file a tax return if you are less then 65 years old and have at least $12,000 in taxable income. If you are older than 65, the threshold increases to $13,400.