Is there a minimum earning before they take out federal tax?

If you begin to earn more you will have federal tax withheld which you may get back next year.

There's no one number that's the limit. Depends on a number of things like your age, filing status, whether you're a dependent. The $400 is the limit for self employment income - you'd have to file at that point, and pay self employment tax for social security and medicare, not income tax. The limit is $5800, for someone whose income is on a W-2, if they are a dependent. If they'r not a dependent, 9500. These limits go up a little almost every year - these numbers are for 2011. Numbers are slightly higher for people 65 and older, and someone filing as head of household. There are still other limits for dependents with unearned income, and for someone filing as married filing separately.

Federal income taxes are based upon your income. The lower your income, the lower the rate. Additionally, the first $9,350 ($5,700 if you're a dependent) isn't taxed at all, so yes, it's entirely possible that no tax would be withheld if your wages are low.

try this pdf doc: http://www.irs.gov/pub/irs-pdf/i1040tt.pdf

it is the IRS tax brackets.

there are minimum paycheck amount of every paycheck that enable the federal and state tax out of your paycheck. I work part time too, but get two paychecks for weekend\days. so sometimes i do not work enough hours on the weekend and therefore the federal taxes are not taken from that specific paycheck.

but when you will be doing your overall taxes (due april 15th) you will know how much all together you had to pay...

also, on your w4 document you might have indicated that you dont want the taxes to e taken away from your paycheck. by doing so you actually said that you will pay them all together at the end of the year. ask your boss to look again at your w4 to clarify that point.

yes, the withholding schedules have different minimums per the frequency of the payroll, ie. weekly, biweekly, monthly etc.

when the gross does not exceed this minimum amount, no income taxes are withheld