As policymakers implement the Affordable Care Act's Medicaid expansion and health insurance exchanges, or marketplaces, they will need to ensure that newly covered individuals are able to make a smooth transition to Medicare when they turn 65 or become disabled, say the Medicare Rights Center's Joe Baker and Doug Goggin-Callahan in a new Commonwealth Fund blog post. People who become eligible for Medicare in states without a comprehensive transition plan, they note, could face gaps in coverage and avoidable out-of-pocket costs.