FYI, the most likely reason to ask for your SSN is to pull a credit report. The overwhelming majority (90+%) of auto insurance companies use credit as an underwriting factor in states that allow it to be used.

Using credit is a touchy subject, but it has been shown to be a powerful predictor of future claims. If anyone is interested in delving more deeply into the topic here are a couple of reports

EPIC Actuaries, LLC -- The Relationship of Credit-Based Insurance Scores to Private Passenger Automobile Loss Propensity -- http://www.ask-epic.com/Publications...res_062003.pdf

University of Texas -- A Statistical Analysis of the Relationship between Credit History and Insurance Losses -- http://www.utexas.edu/depts/bbr/bbr_creditstudy.pdf