I am an IT worker who may not get a W-9 (I've heard that's where the money is supposed to come). For tax withholding only can I do this. It's pretty simple. It is a tax withholding on your paychecks only. Furthermore, it doesn't need to be a certified copy. I want it in case I get a TCA letter. I got mine in September, but I was using my W-9 (see above), and was instructed to do it as that was what they gave for tax withholding only. It has nothing to do with you getting an actual W-10 or W2.