Medi-Cal implemented the use of the CMS-1500 claim form on June 25, 2007. Providers who previously submitted claims on the HCFA 1500 must bill on the new CMS-1500 claim form immediately. Providers not using the new CMS-1500 should be in the process of transitioning. Failure to use the new form for claims submitted after June 25, 2007 may result in rejection of the provider's claim