Paying bank means -
(1) The bank by which an item is payable unless the item is payable or collectible at or through another bank and is sent to the other bank for payment or collection;
(2) The bank at or through which an item is payable or collectible and to which it sent for payment or collection; or
(3) The bank whose routing number appears on a check in the MICR line or in fractional form (or in the MICR-line information that accompanies an electronic item) and to which the check is sent for payment or collection.
12 CFR § 210.2
As used in this subpart, unless the context otherwise requires: