Can you file a tax return after Oct. 15, if taxable income is under $4,000?

Taxable income and earned income are not necessarily the same thing. If you only earned 4000 all year you can file for a refund of the taxes taken out. Next year if you only earn 4000 then file exempt on your W4 and they wont take out state or federal taxes. If you owe taxes on 4000 above your deductions then get it filed ASAP or the fines will add up. You certainly can file it after Oct 15 but it will cost you more.