Customs support policies are used to enhance the competitiveness of knowledge-based firms by reducing costs, facilitating access to production inputs, and strengthening innovation capacity. The aim of this study is to develop a framework for evaluating customs support programs in Iran. This research adopts a mixed-methods approach. First, an evaluation framework was developed through a review of the literature, analysis of policy documents, and consultation with experts. The framework distinguishes three levels of evaluation: outputs (e.g., process facilitation and cost reduction), outcomes (improvements in firm performance), and impacts (export growth and enhanced competitiveness). Second, the support programs were assessed using available implementation data. Given the recent implementation of programs and the limited availability of firm-level performance data, the analysis focuses on outputs and outcomes. The geographical scope of the study covers knowledge-based firms in Iran, while the temporal scope spans the implementation periods of the programs, mainly from 2016 to 2025. The findings indicate that support policies have contributed to streamlining procedures, reducing administrative barriers, and improving firms’ access to inputs and equipment. However, their contribution to improvements in firms’ economic and innovation performance cannot be assessed. Therefore, strengthening evaluation systems, developing integrated data infrastructures, and aligning customs support measures with broader innovation policy objectives are essential prerequisites for assessing the long-term impacts of these policies.