In today's digital era, school financial management faces challenges in transparency, efficiency, and reporting accuracy. This study aims to design a web-based Financial Information System (FIS) to support financial management at SMA Al-Kadar. The system was developed using the waterfall method, which includes stages of needs analysis, design, implementation, and black box testing. This system assists the school, parents, and students in managing payments, reporting, and other financial transactions more transparently and efficiently. The research results show that the implementation of the web-based FIS can improve transparency, minimize administrative errors, and support data-driven decision-making. Therefore, this financial information system is expected to optimally support the school's financial performance.