A customer came in to open an account. He gave us his tax id number card which is ITIN. However, when we pulled the decision power with using his ITIN, it said that there is a SSN associated with that person. He said that to his knowledge, he has never been issued a SSN and that he has been filing his tax returns with his ITIN. Is this normal? If so, do we use the ITIN for the account?

I am only speculating, but chances are the social security number was used to obtain employment. The IRS came up with ITINs so that illegal immigrants could still file tax returns but not do so using the stolen social security number.

From a CIP perspective you have a substantial descepency that you must resolve by following your procedures.

I have a question that is somewhat related. Does the IRS issue an ITIN card or do they just issue a number?

No card, just a letter.