Fundamental shifts in the tax regime and the imperative transition from conventional paradigms toward data-driven governance necessitate the adaptability and capacity-building of human capital. Nonetheless, a conspicuous disconnect between tax auditors’ individual competencies and prevailing organizational structural inertia impedes the efficacious implementation of emerging tax policies. In this regard, the lack of a coherent theoretical and analytical framework to conceptualize the measurement and enhancement of human capital efficacy mandates the development of a comprehensive conceptual model throughout this strategic transition. This study aims to design a conceptual model for human capital performance evaluation in the operationalization of modern tax legislation. Methodologically, this inquiry adopts an applied-fundamental objective and employs a qualitative approach grounded in Strauss and Corbin’s Grounded Theory strategy. Empirical data were gathered via in-depth, semi-structured interviews with eight experts and domain specialists across taxation and human resource management, with purposive sampling sustained until reaching theoretical saturation. Data analysis was executed through three iterative coding phases open, axial, and selective culminating in the extraction of core categories and subcategories. The qualitative findings are synthesized into a paradigm model encompassing causal conditions, the central phenomenon (human capital performance evaluation), contextual conditions, intervening conditions, action/interaction strategies, and consequences. The analytical results elucidate that contextual conditions (comprising organizational and technological infrastructures) serve as the most deterministic factor in shaping evaluative strategies; concurrently, the paradox between emerging digital proficiencies and critical deficits in data-driven analytical capabilities warrants focal strategic interventions. Grounded in the derived conceptual model, the efficacious execution of modern tax laws is contingent upon re-engineering contextual architectures to overcome organizational inertia and align individual proficiencies with data-centric imperatives a prerequisite for realizing desired outcomes across the contemporary tax administration.