YES. Get excited. We're talking about Check 21. “WHAT?!” Yeah, you read that right! Back in October 2004, the Check Clearing for the 21st Century Act, also known as Check 21, went into effect and is covered in Subpart D of Regulation CC. authorizes the use of a negotiable instrument called a “substitute check.” Check 21 provides the legal framework for the creation of these types of checks, which can then be used in place of the original paper check, without an agreement in place with other financial institutions. Prepare yourself for the wonder of Check 21. Let's dive in.