This research delves into the intricate web of corruption perceptions and experiences across the Portuguese-Spanish border, shedding light on the nuanced interplay between individual tolerance towards corruption and the geographical boundaries that ostensibly confine such attitudes. Utilizing a comprehensive survey approach, we engaged 1020 Portuguese citizens and 1506 Spanish citizens, employing 11 carefully crafted life-based scenarios to gauge their tolerance towards corruption. Surprisingly, when analyzing these scenarios in isolation, we found no discernible spillover effects, indicating that corruption tolerance appears to remain largely contained within national borders. However, the narrative takes an intriguing turn when exploring citizens' personal encounters with corruption. Our findings reveal a noteworthy transboundary impact: the experience of corruption by individuals on one side of the border significantly influences the corruption tolerance of their counterparts across the divide. This phenomenon underscores the interconnectedness of corruption experiences, transcending geographical barriers and highlighting the need for a more nuanced understanding of cross-border dynamics. Methodologically, we employed the stochastic frontier approach to dissect the multifaceted dimensions of corruption tolerance. In conclusion, our study contributes significantly to the growing body of knowledge on corruption by unraveling the intricate mechanisms of spillover effects across the Portuguese-Spanish border. The divergence between tolerance-based scenarios and experiential impacts challenges conventional notions of contained corruption attitudes, urging scholars and policymakers to adopt a more holistic perspective. As corruption remains a pervasive global challenge, understanding the cross-border dynamics revealed in this study becomes imperative for designing effective interventions and fostering regional integrity.