The best thing you can do to prepare for your credit card conversion is to review your current servicing program and procedures. Also your disclosure documents are important to understand.  A review all cards records in your portfolio for accurate relationship account information is strongly recommended. 

 The field which holds the CU*BASE account number is called the "relationship" account. This is the account number the new credit card loan and associated information is converted. In order to have an accurate data conversion, correct relationship account bases must be linked to all credit cards. 

You should obtain a listing from your credit card processor which contains your cardholder base, listing both card number and associated relationship number.  Next you need to review that all cards have a valid relationship account number in this field on credit card processor's database.

Here are items to look for: No blank records, only the membership base is entered (no suffix at the end), all relationship accounts exist as an active CU*BASE member (no closed memberships), and the account number is not for a joint owner on the cardholder's credit card number.  In addition, a common error we see is inverted numbers or digits.  

Although this make take some time, it is time well spent before the credit card loan accounts are created.