How low can you make not to have federal tax come out of check?

You DO NOT EVER HAVE ANY AMOUNT WITHHELD FROM YOUR NET TAKE HOME PAYCHECK.

From your gross pay wages this amount would depend on the information that you entered on your W-4 form that you filled out correctly and gave to your employer payroll department. You should ask the employer payroll department for the answer that you think you need for this question as they would would be the only one that would know the correct amounts of all of the different withholding amounts that they will be required from your gross wages NOT from your NET take home pay check.