A couple clients have received Form W-9 from Chase Bank, asking for their SSN.  These people do not have accounts at the bank that would generate a 1099, which is the only legitimate purpose for using the W-9.  Instead they have credit card accounts, opened by one spouse with another card for the other whose SSN is missing.  I think in both cases, the credit card account was opened before the marriage.  If the bank thinks it needs the SSN, that's fine.  But the W-9 is not the way to ask for it. 

One client went to the bank and asked a manager why they were using an IRS form.  "That's just the form we use," she was told.