Question: The new ICD-9 codes go into effect Oct. 1, but the payment changes take effect until Jan. 1. Will CMS do a special implementation date for case mix changes retro to Oct. 1, or do agencies miss out on the case mix bump in the last quarter of the year? Vermont Subscriber Answer: Changes to the case mix list are effective October 1, 2011. These changes bring no surprises, but do include case mix codes that were expanded to include fifth digits. This means that those new codes will add points to the case mix score when they are earned. Payment changes are expected to take place on January 1, 2012 (the rules are only proposed at this time).