This report presents the findings of Work Package 2 (WP2) of the Horizon Europe project Sustaining Public Administration in Modern Democracies (SUPA). It examines regulatory offsetting schemes, commonly known as “One-in-One-out” (OIOO) or “One-in-X-out” (OIXO), which require new regulatory burdens to be compensated through reductions in existing burdens. As regulation and its associated burdens have continued to grow, modern democracies have increasingly adopted these schemes within broader Better Regulation programmes. Nevertheless, systematic comparative evidence of their design and implementation remains limited. Therefore, this report examines the design, politics, implementation and effectiveness of regulatory offsetting and the conditions under which it constrains regulatory growth and provides meaningful burden relief.

The report combines documentary analysis, longitudinal quantitative analysis and qualitative case studies drawing on 63 elite and expert interviews. Part I maps regulatory offsetting and selected burden reduction initiatives across 28 countries and the European Union (EU), including more detailed examinations of the Netherlands and the EU. Part II analyses legislative activity in Denmark, France, Germany and Spain between 2000 and 2025, using the Netherlands and Norway as comparison cases. It examines whether offsetting is associated with changes in the number and volume of legal acts and in the prevalence of restrictive and termination clauses. Part III investigates the practical operation of offsetting through in-depth case studies of Denmark, France, Germany and Spain.

Overall, the findings reveal that offsetting has its clearest and most consistent effects on regulatory procedures and institutional behaviour, particularly on how regulation is assessed and designed. It raises awareness of regulatory burdens, institutionalises cost measurement, strengthens the assessment, justification and scrutiny of regulatory costs, and encourages officials to consider less burdensome approaches to regulatory design and implementation. Yet we find no clear evidence that offsetting consistently constrains rule growth or provides substantial relief to regulated actors. Four main findings support this conclusion.