We would recommend using the bank’s legal name for all legal documents, including loan agreements, as required by the FFIEC’s Interagency Statement: Branch Names. The legal name is a bank’s “full name as reflected in its charter.” We also note that nothing in Illinois or federal law requires you to register a divisional or trade name if it is always used in conjunction with your legal name. Of course, you should train staff to avoid customer confusion about the divisional or trade name, as discussed in the Interagency Statement.