International Tax Reform in the Digital Economy: Theoretical Framework and Empirical Simulation of Multi-Factor Allocation Systems

The digital transformation of the global economy has fundamentally challenged established principles of international taxation, creating urgent demands for policy reform that aligns tax systems with the realities of digital business models. This study presents an empirical evaluation of a four-factor formulary apportionment system (FAS) as an alternative to current transfer pricing mechanisms for taxation in the digital economy. A quantitative simulation methodology is applied to assess redistributive effects and implementation characteristics across twelve representative jurisdictions. The research employs a controlled experimental design using user participation, digital sales, digital assets, and R&D activities as allocation factors, with equal baseline weights of 25% applied to a standardized global profit pool of $50 billion. The analysis includes a baseline impact assessment, sensitivity testing of factor weights, and a comparison with alternative taxation approaches, such as transfer pricing regimes, sales-only formulas, and simplified OECD Pillar One models. Empirical results reveal substantial redistributive effects under the four-factor system, with tax base reallocations ranging from gains exceeding 180% to losses approaching 40%. The findings demonstrate a systematic reallocation from low-tax jurisdictions benefiting from current profit-shifting practices toward market jurisdictions with substantial user bases, sales presence, and economic substance. Sensitivity analysis across seven weighting scenarios reveals that jurisdictions are highly responsive to the user factor, confirming its critical role in digital value creation. These results provide strong empirical support for reforming international tax rules by integrating multi-factor allocation methods that better reflect the borderless and intangible nature of digital business. While offering promising redistribution potential, implementation challenges remain– particularly concerning factor weight stability and global coordination. The study provides quantitative evidence to inform policy debates, suggesting that effective reform necessitates moving beyond incremental changes to adopt comprehensive, formula-based models.