There are no laws in your favor. You can chose not to give your social security number and your employer can chose not to keep you employed. Social Security numbers are used for several legitmate reasons by your employer and the federal and state government, cheif among them to properly identify you for the purpose of collecting taxes and making determinations about how much Social Security payments you are entitled to (hence the name). Your Social Security number was not a birth rite it was given to you by the government, to fulfill the government purposes. Your employer needs it for the above mentioned reasons and probably to make sure you get paid properly, to make sure their taxes are paid correctly, to identify you for other benefits, etc. If you are paranoid about the security of your social security number, and you dont trust your employer, you should probably not work for that employer.