October 1, 2015 changed the way we code. Documentation, accurate coding and mapping to the most appropriate MS-DRG is crucial to your bottom line. Grouper logic in ICD-9 and ICD-10 is NOT always a 1:1 map. Understanding how the logic changed and recognizing the importance of documentation and correct coding will help assure appropriate MS-DRG assignment leading to correct reimbursement and data quality.