This Note documents Greece’s comprehensive tax administration reform journey over 2010–2025, showing how sustained reform under crisis conditions translated institutional change and digital innovation into durable revenue, compliance gains. Following an initial phase focused on revenue stabilization, Greece progressively advanced legal and institutional reforms, culminating in the establishment of the Independent Authority for Public Revenue (IAPR), followed by an ambitious digital transformation centered on myDATA, e invoicing, real time reporting, and data driven compliance management. These reforms contributed to a marked increase in the tax to GDP ratio, a sharp reduction in the VAT compliance gap, and significant improvements in operational performance, as reflected in international assessment tools such as TADAT and ISORA. IMF capacity development, supported by other development partners and strong ownership by the Greek tax authority, played a critical role in reform design, implementation, and monitoring. Greece’s experience underscores the importance of credible governance reforms, appropriate sequencing, sustained political commitment, and investment in digital and human capital. While country contexts differ, the lessons from Greece are highly relevant for other countries seeking to modernize tax administration, strengthen compliance, and enhance domestic revenue mobilization over the medium term.