As long as you are registering on the company's secure website, no problem. Ath is a good company. Below is a list of abut 200 companies to sign up with. Most of them will require either a SS# or EIN before you get paid for any work with them. In fact, because they are required to keep track of and report what they pay, for tax purposes, be suspicious if they don't ask for your SS or EIN. Most of the scammers who send checks don't ask for your information because they don't plan to pay you and they don't pay taxes on their income after they've scammed you.