You do not need separate encounter notes, but each service must have enough documentation to stand alone. For a wellness visit, documentation needs 10 ROS and a comprehensive physical exam, an assessment with the appropriate Z00.XX code, and any additional plan documentation as required (like Medicare's falls assessment, etc.); to bill an E&M in addition to wellness, the E&M needs a separate complaint, affected systems review, pertinent systems examined (if applicable, and cannot be counted towards wellness too), and MDM that supports the level billed.