Do you really mean no withholding? No state, federal, social security or medicare taxes? That's a complicated situation and you need to tell us more about your job.
Or do you mean, you get a pay check and there is medicare and social security withholding but no federal tax withholding? You may just need to submit a new W-4 to your employer.
My employer DOES withhold social security and medicare taxes. Just not Federal. I guess I have earned more than last year so I will change my W-4. Thanks.
Use the worksheet and claim the number of allowances it suggests. The method is self-adjusting; more is withheld in weeks you earn more and less is withheld when you earn less.