Who has the right to ask for your SSN?

While any business or agency can ask for your number, few can actually demand it – the exceptions are motor vehicle departments, tax departments and welfare departments. Also, SSNs are required for transactions involving taxes, so that means banks, brokerages, employers, and the like also have a legitimate need for your SSN.

Most other businesses have no legal right to demand your number.
"There is no law prohibiting a business from asking for your Social Security number, but people don't know they can say no," says Carolyn Cheezum of the Social Security Administration.
"We recommend that you ask if they'll accept an alternative piece of identification. If they don't, flat-out refuse to do business with them. Bear in mind that there's a possibility they'll refuse to provide whatever product or service you're seeking."

“When you go to the doctor's office and fill out the medical information, they ask for the SSN. I leave it blank. Nothing happens. I'm not reporting income from them."

In fact, chances are good that many companies that routinely ask for SSNs will do business with you even if you refuse giving them your SSN. Most companies have alternative customer ID numbers but will only offer you one upon request. For instance, in order to open an account at a utility company, you may asked to fill out a questionnaire to determine payment history (all based on honesty). Questionnaires help companies determine ratings, which determines whether customers have to pay a deposit to establish service.

Linda Foley of the Identity Theft Research Center says she brought her critically ill cat to a vet's office and balked when she was asked for her SSN. "I said why? Will it be my cat's ID number?” They said “No, but if you give us a check we want a driver's license and a SSN in case the check bounces.” I said I'd pay by credit card. They said it's our policy to get the number. I said, “If I give you a credit card and refuse to give you my Social Security number you'd let my cat die right now?” They looked at me and the cat and said, “Give us the card; we'll take care of it.” I was upset about the cat, but I was frustrated by the way I was being treated. It was unnecessary."

(This is a partial reprint from Yahoo Finance – for more information, visit their website at: http://finance.yahoo.com/banking )