The Centers for Medicare & Medicaid Services recently finished mailing new Medicare cards to beneficiaries, which replace the Social Security-based number on their previous cards with a new Medicare beneficiary identifier, the agency recently announced. The Medicare Access and CHIP Reauthorization Act of 2015 required the agency to distribute the new cards by April 2019 to protect against identity theft and fraud. Health care providers have until the end of this year to transition to the new identifier for billing and other Medicare transactions. As of last week, 58 percent of Medicare fee-for-service claims included the MBI, demonstrating a smooth transition to the new cards, the agency said.