No. A social security number in the context a credit reporting is simply a unique identifier, and is defiantly one way to accurately identify someone in the credit bureau databases. Another way is through a full name and home address. This assumes two things though: 1. The name and address are uniquye to that person (a jr./sr/ would need a date of birth and/or social), 2. the name and home address have been reported to the credit bureaus via a trade line or other means. If you client gave you their new address on a rental property, and that new address is not on a credit card or loan, the bureaus may not be able to find you and we would then need a date of birth or social.