Determinants of Bilateral Readmission Agreements: Incentives, Alignment, and Historical Ties Between EU Member States and Third Countries

This study investigates what factors predict when EU member states conclude bilateral readmission agreements with non-EU countries for returning irregular migrants. As of 2024, EU member states have signed 351 such agreements, yet the determinants of these arrangements remain insufficiently understood. This inquiry is important given the asymmetry of interests in readmission cooperation: while EU countries seek to facilitate deportations, origin countries often face political and economic costs in accepting returnees. We address two gaps in the literature. First, prior qualitative case studies lack generalizability across the broad range of partner countries. Second, little is known about the relative importance of competing explanatory factors. Understanding these mechanisms can inform policymakers about what factors shape third countries’ willingness to cooperate on return migration governance. Building on the external incentives and social learning models, we argue that readmission cooperation is shaped by material inducements and normative convergence as well as by asymmetric interdependence and historical relationships. The EU's leverage through aid and market access provides incentives, while shared norms and political alignment foster receptivity. Yet incentives and alignment may be subjected to structural power asymmetries and colonial or political ties. We test these hypotheses using a panel dataset covering EU-third country dyads from 2009 onward (N = 48,590 country-year observations). Logistic regression models with fixed effects account for time trends and country-specific trajectories, with all predictors lagged by one year to ensure temporal ordering. We find that the likelihood of readmission agreement is associated with aid (β = 0.082), former colonial dyads (β = 0.773), and alignment in UN voting (β = 0.824), indicating that migration cooperation is embedded in broader bilateral relationships. However, several results challenge conventional expectations. Administrative capacity does not significantly predict agreements, while EU candidacy and visa waiver status are linked with lower likelihoods (β = -1.197 and β = -0.675), possibly reflecting reliance on EU-wide frameworks. These findings challenge the assumption that readmission cooperation follows a purely transactional logic. Beyond material incentives, historical relationships and political alignment emerge as key determinants of EU return migration diplomacy.