This technical assistance (TA) report presents the outcomes of the multi-year National Reserve Bank of Tonga (NRBT) Forecasting and Policy Analysis System (FPAS) TA project, conducted between late-2021 and mid-2025 over a total of eleven missions, five in-person and six virtual. The project focused on building new institutional capacity for model-based policy analysis and macroeconomic forecasting, along its integration into monetary policy processes and external communications. NRBT staff made remarkable progress and built a strong skillset for providing analytical support to policymakers. Model-based work plays an important role in the NRBT internal discussions and represents an important input in forward-looking monetary policy formulation. Recommendations relate to ensuring FPAS work sustainability and further streamlining external communications.