We are planning a restructure of our deposit accounts for early 2023. Because Reg DD requires we notify existing customers of the changes, we will be mailing a letter outlining the changes and enclosing the new TISA disclosure. The plan is to generate a report as of a certain date, (let's say January 15) to obtain the existing customer population. Then from that date forward "double disclose" (current TISA and new TISA disclosure) to anyone who opens a new account until implementation on February 1.

I've been wracking my brain for a way to avoid the "double disclosure", which may be confusing for staff and customers. Any ideas out there?

Schedule the conversion for existing customers 30 days after the initial rollout of your new accounts. You'll give your staff time to get the kinks out of the sales pitch for a period of time, before dealing with existing customers 30 days later.