Under the terms of the Check 21 Act, banks can create a substitute check from an image of the original check. The legal equivalent of the original paper check, Check 21 substitute checks allow banks to eliminate the paper shuffle that was the hallmark of the traditional check processing system.
Substitute checks are paper copies created from electronic images of original paper checks (front and back, with all endorsements). Each substitute check also includes a statement identifying it as a legal copy of the original check. The original check may then be destroyed once it is digitized. Because substitute checks pass through fewer hands, they post to your account much more quickly than under the traditional processing method.