I work as an independent contractor and I do freelance for several different companies. When I first begin an assignment for these companies I don't know a lot about them. Actually, I know practically nothing about some of the companies I do work for in the beginning. Anyway, I have to give them some type of identification number before I get paid.
I always use my social security number, but a friend suggested that I get an individual taxpayer identification number so that I don't have to give my social security number to as many people, especially when I only deal with some of the companies through the Internet.
We all know what can happen when your social security number gets into the wrong hands, so my friend says the tax ID number is safer for me and easier for business purposes too.