This book offers the first comprehensive legal analysis of how successive crises have reshaped the EU's financial constitution.

Long considered a technical and overlooked field, the EU budget has undergone a profound reconfiguration following the COVID-19 pandemic, Russia's war against Ukraine, and the emergence of ambitious defence and green-transition initiatives. This book argues that these developments do not amount to an ad hoc “patchwork,” but instead signal the consolidation of a coherent new financial order operating alongside the traditional EU budget.

Drawing on a law-in-context methodology, Rosalba Famà systematically reconstructs the traditional constitutional foundations of the EU budget and examines how post-2020 financial innovations - joint borrowing, externalised financing, and progress-based disbursement - challenge long-standing principles of EU public finance. The book shows how the EU's borrowing operations have evolved into a sovereign-style “debt machine,” how external revenues have created a de facto parallel budget, and how results-based financing is transforming funding governance.

The analysis maps the constitutional implications of this dual structure for institutional balance, democratic accountability, long-term debt sustainability, and the distribution of powers among the EU institutions. Combining doctrinal, contextual, economic, and archival insights, the book offers a nuanced account of the EU's evolving fiscal architecture at a pivotal historical moment.

Ultimately, The Transformation of the European Union Budget reframes the EU's financial evolution as a step toward a more sovereign-like model of collective action-and proposes concrete reforms to ensure that flexibility is balanced with legitimacy: no common debt without representation.