This dataset identifies California’s eligibility groups by aid code. California uses aid codes to account for eligibility group populations and the eligibility requirements, scope of benefits, services, costs, claims, encounter data, and managed care arrangements related to those populations. Aid codes in this dataset are mapped to the Transformed Medicaid Statistical Information System (T-MSIS) eligibility group descriptions and codes. California uses this mapping to submit claims data, enrollee encounter data, and supporting information to the Centers for Medicare & Medicaid Services (CMS), as required by Section 4735 of the Balanced Budget Act of 1997 and Section 6504 of the Affordable Care Act for the purpose of program integrity, program oversight, and administration. This dataset includes aid codes that do not have Medi-Cal benefits or have benefits and are not federal programs. Some aid codes may appear to be identical but possess distinct benefits or grouping factors. An aid code may appear more than once if multiple populations are represented in one aid code and can be identified and mapped to distinct T-MSIS groups.