I could expect a request for this when nearing the closing and see that all the time. But this far ahead? My guess is that he is either getting everything well ahead of time or, more likely, is going to use it to pull a credit report. Perhaps the owner has asked him to qualify buyers. I rarely give mine out - there are too many scammers out there and I keep as closely held as I can. The fact is that it is illegal to use the Social Security number for any purpose other than something which is tax-related. Banks will need it - eventually - as they have to report income. This illegality is largely ignored today and people are becoming conditioned to give their numbers whenever asked. Businesses often use it instead of creating their own unique numbers, illegal or not. Would you give our your password? How would you feel if you learned that someone else was getting your social security money? It may pay to keep it close and not give it out too readily.