The FCHIP Extension Act extends the Frontier Community Health Integration Project Demonstration, a Medicare program that tests new ways to deliver health care in frontier communities, by doubling the demonstration period from five years to ten years. The extension becomes effective on December 31, 2026, allowing the program to continue operating under its original authorization for an additional five years beyond its initial timeline. This demonstration primarily affects rural and frontier health care providers and Medicare beneficiaries in those areas who participate in integrated care delivery models. The bill does not specify new funding amounts, instead extending the existing demonstration's authorization and allowing it to continue using its current appropriations. By lengthening the program, Congress aims to give frontier communities more time to test and potentially expand innovative health care integration approaches.