Digital transformation has become a cornerstone of modern fiscal governance, reshaping how governments collect, manage, and monitor public revenues in ways that affect efficiency, equity, and trust. This study investigates how the digitalization of fiscal administration influences tax compliance, administrative costs, and transparency in emerging economies, using a comparative analysis of Uzbekistan, Kazakhstan, and Indonesia (2018-2024). We integrate descriptive statistics with a policy/process review of flagship platforms - E-Nalog and MyTax (Uzbekistan), E-Salyk (Kazakhstan), and DJP Online (Indonesia) - to quantify behavioral and institutional change. Results indicate that comprehensive E-tax adoption is associated with sizable compliance gains (≈17-22 percentage points), reductions in operational costs of up to ~40%, and measurable improvements in taxpayer satisfaction and perceived fairness, consistent with a “service + deterrence” model of compliance (simplified filing, real-time validation, analytics-driven audits). These effects are strongest when portals are interoperable with customs, banking, and social funds, enabling pre-filled returns, faster refunds, and risk-based case selection.