This bill, titled the Fostering Learning and Excellence in Charter Schools Act (FLEX Act), aims to enhance flexibility and support within federal programs for charter schools by amending the Elementary and Secondary Education Act of 1965. It modifies funding allotments, increasing the minimum percentages reserved for charter school facilities assistance, national activities, and grants to support high-quality charter schools. Specifically, it raises the reservation for facilities assistance to at least 15 percent and for national activities to at least 25 percent, while reserving at least 30 percent for high-quality charter school grants. The legislation significantly expands the eligible uses of grant funds for charter schools. It allows funding to support the addition or expansion of curricular or other offerings at high-quality charter schools, such as new academic programs, personalized learning, or new curricular approaches, provided these expansions enable additional student enrollment. Furthermore, it broadens eligible expenditures to include hiring and compensating teachers and school leaders, academic subscriptions, curricular support, necessary renovations and facilities repairs, and costs associated with the operations and management of charter school facilities. The bill also introduces several procedural and regulatory changes. It permits State entities to use an eligible applicant's approved charter authorization application in lieu of a separate application for subgrants, streamlining the process. State entities are now required to ensure that charter schools receiving funds address the transportation needs of their students. Additionally, the Secretary of Education is mandated to consult with charter school operators prior to issuing proposed rulemaking and to promulgate only necessary regulations, avoiding additional nonstatutory requirements. Regarding national activities, the bill modifies how funds are used, including providing support and technical assistance to State entities, disseminating best practices, and increasing access to facilities for charter schools. It prioritizes increasing charter school seats in states with recent supportive legislation, and for rural students and students with disabilities. The amendments also allow grants to charter management organizations to plan for operating or managing high-quality charter schools in new states or those with limited charter school options, fostering broader reach and impact.