I'm considering changing my tax status for a few months with my present full time employer from 2 (married filing jointly) to exempt. My husband is disabled and we need extra money coming in. I want to know is it legal and for how long can I do it for? Also when I file exempt does that stop FICA and Medicare taxes from being taken out of my paycheck, or just the federal income tax? Is there a separate form I should be filling out to stop the FICA and Medicare withholding as well? I assume that I will have to pay back the money that wasn't withheld on my tax return filing in 2011.