"Item" under the UCC does not include EFT transfers that are subject to Regulation E. There is no need to, and I don't recommend, cutting down on the Reg E lead time for stops in order to make them look like stops on "items."
And yes, the rule requiring you to accept a stop payment order on an item on the day following presentment of that item can be found in the UCC. section 4-303(a)(5) if the item hasn't already been paid in cash, certified, or otherwise become accountable for the item.
If I issue a check to Randy and it is presented to my bank in a cash letter today, August 29, 2016, and I call the bank before its cutoff hour (as defined in 4-303(a)(5)) on Tuesday, August 30, to stop payment on the check, the stop order is timely. If the bank hasn't paid attention to the UCC and hasn't established a cutoff hour for the purpose of this section of the UCC, the cutoff hour is the close of business on Tuesday.
So you should adopt a reasonable cutoff hour in accordance with the UCC and include it in your deposit terms and conditions concerning stop payments.
And by the way, if the check I wanted to stop happens to have overdrawn my account in last night's posting, if I make the cutoff hour, and the stop payment is timely, you're going to have to make things like the check did not overdraw the account -- no OD counter increase, no fee, etc., and you'd better return the check "stop payment" and not "NSF" or "overdrawn."
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John S. Burnett
BankersOnline.com
Fighting for Compliance since 1976
Bankers' Threads User #8