The MAGNET Act expands and modernizes the federal Magnet Schools Assistance Program to promote school integration and diversity. The bill allows state educational agencies to apply for grants alongside local school districts, increases annual authorization to $109 million through 2031, and establishes new grant criteria prioritizing whole-school magnet programs, inter-district choice initiatives, and inclusive enrollment practices that benefit entire districts. School districts can receive up to $7.5 million over five years to develop programs that recruit diverse student populations, improve infrastructure, recruit quality teachers, provide free transportation, and engage families in program development, with priority given to first-time applicants and districts that haven't received similar funding in the past three years. Recipients must submit annual reports documenting improvements in student diversity and academic achievement, and the Secretary of Education can require remedial plans or withhold remaining funds if sufficient progress isn't made within two years.