Objective: This study develops and analyzes a dynamic Cash Waqf Takaful model as a sustainable Sharia-compliant solution to improve the welfare of Indonesia's elderly population. By integrating cash waqf and takaful, the model aims to provide financial and health protection for economically vulnerable seniors. Method: Using a system dynamics approach with Vensim PLE 10.2.2, we simulate interactions among waqf contributions, takaful claims, investment returns (ROI), and macroeconomic factors (inflation, GDP growth, demographic shifts). The model is validated against historical data (2020-2023) and tested under three GDP scenarios (4%, 3%, 2%) to assess system sustainability. Results: Indonesia's dependency ratio is projected to increase from 46.3 (2015) to 53.4 (2045), intensifying pressure on the working-age population. The Cash Waqf Takaful model effectively subsidizes premiums for the elderly through Waqf Fund investment returns. However, system stability requires minimum GDP growth of 3–4%; GDP decline to 2% demands higher ROI or additional subsidies. Inflation above 5% erodes purchasing power, reducing premium contributions and threatening sustainability. We identify four key feedback loops (two reinforcing, two balancing) governing system dynamics. Conclusion: Cash Waqf Takaful offers a resilient, innovative solution to Indonesia's aging population challenges by ensuring financial inclusion and social protection. The model's long-term viability depends on sustained economic growth, prudent fund management, and effective inflation control. Recommendations: Regulators should promote productive waqf investments; takaful operators should design elderly-friendly products; waqf institutions must enhance transparency. The government should provide subsidies and improve public literacy on waqf and takaful to strengthen system sustainability.