The Internal Revenue Service considers all income that is not specifically exempted from taxation to be taxable income, regardless of the age of the person who earned it. If your son is employed, he might have to file an income tax return and pay taxes on a portion of his income, but that doesn't mean he is not your dependent. If he meets IRS dependency requirements, you can still claim him on your tax return.
Age
Your son's age is a primary factor in determining whether you can claim him as a dependent on your federal income tax return, regardless of whether he has a job or not. Your son must be under 19 years as of the last day of the year to qualify as your dependent. If your son is a full-time student you can continue to claim him as a dependent as long as he is under age 24.
Support
If you want to claim your employed son as a dependent on your federal income tax return, he cannot provide more than more than half of his total support for the entire tax year. That doesn't mean you have to provide more than half of his support. You can divide the support between yourself, your son and a third party, and still claim your son as a dependent.
Residence
You and your employed son must share the same principal residence for more than half of the tax year. Temporary absences for performing military service, attending school, hospital stays, business assignments or vacations do not count against your son's time in your principal residence.
Considerations
You cannot claim your employed son as a dependent if someone else, such as a former spouse, claims him as a dependent. In most cases you can't claim your son if he is married, although there are some exceptions to that rule as well. If do you claim your son as a dependent, he can't take a tax exemption for himself when he files his federal income tax return.
