Iu2019m not a tax expert. But, if you worked in the US, then you are subject to federal taxes.I donu2019t know what you mean by u201cmy federal taxes are now zerou201d.A W4 only sets the withholding of estimated taxes. If they withheld zero, you might have earned less than the threshold of owing taxes, but you MUST file a 1040 tax form to reconcile the actual amount earned, the amounts withheld and the amount you are allowed to deduct and the total amount you owe after using the tax tables. It might end up zero after calculations but you are required to file by law, nonetheless.You need to get the 1040EZ form and file by April 15 of the year following when you earned the money.