What do you mean a dependent parent? Are you the parent of a small child but also a dependent of your parents? Or a dependent of a live-in partner? More information might help.
If you are a W-2 worker and your only income is $3000, you do not need to file a return. If you had tax withheld, you can file a return only to claim a refund of the taxes. You can't claim your child as a dependent and you can't claim any other tax benefits. If you do, then you can no longer be claimed as a dependent by someone else, such as your parent or partner.
If you are self-employed, you must file a return because your self-employment income is more than $400. You will pay 15% self-employment tax (the equivalent of social security and medicare tax on a regular paycheck). You do not have to pay income tax, but you still have to pay self-employment tax. As long as you claim no credits or dependents on the income tax part of the return, you can still be claimed as a dependent by someone else even though you are paying self-employment tax.
