The simple answer is to send a full truth in savings disclosure to all customers 30 days in advance and then convert the accounts to the new account type.
You are only technically required to provide a change in terms notice if:
Change in terms. (1) Advance notice required. A depository institution shall give advance notice to affected consumers of any change in a term required to be disclosed under Sec. 1030.4(b) of this part if the change may reduce the annual percentage yield or adversely affect the consumer. The notice shall include the effective date of the change. The notice shall be mailed or delivered at least 30 calendar days before the effective date of the change.
James M. Moore, CRCM
My postings are not legal advice and may not be endorsed by my employer.