KCMU briefs examine CMS rules governing changes to Medicaid eligibility and enrollment: Two new briefs from the Kaiser Family Foundation's Commission on Medicaid and the Uninsured (KCMU) examine changes to Medicaid eligibility and enrollment rules under the Affordable Care Act (ACA) and how such changes are expected to affect beneficiaries, including people with disabilities. An 18-page brief provides a summary of the final rule issued by the Centers for Medicare and Medicaid Services (CMS) to implement ACA provisions related to Medicaid eligibility, enrollment simplification, and coordination (www.kff.org/medicaid/8391.cfm). Achieving the goals described in the rule, which becomes effective January 1, 2014, will require state Medicaid agencies to make substantial process and system changes and to work closely with the new health insurance exchanges and other insurance affordability programs. Even with sophisticated systems in place, the authors note, the full potential of the ACA will not be realized unless agencies provide the substantial navigation assistance that many eligible individuals will need. A companion brief (www.kff.org/medicaid/8390.cfm) provides a short summary of current Medicaid eligibility and benefits for people with disabilities and explains how they will be affected by the ACA in light of CMS's new regulations. It also describes how provisions for the new health insurance exchanges affect Medicaid eligibility determinations for people with disabilities.