We have 2 banks that merged together and we want to change the cut-off time for the branches. It had been 3pm and we are going to change it to 2pm. Do we have any requirements to notify the customers within 30 days before the change? I know we will give the customer some notification but does it need to be 30 days. Please give me the part of the Reg if we have to. Thanks.

It is part of your availaibility disclosure as required by 226.16.(b)(2): "including a description of the bank's business days and when a deposit is considered received".

A shift in your cut-off schedule to an hour earlier negatively impacts your "business day", so a 30 day notice is required.