The Spanish Institute for Fiscal Studies has awarded funding to ENT researchers for the project “Pay-As-You-Throw Waste Fees: Experiences, Barriers, and Challenges in Spain”. This project aims to gather knowledge and the state-of-the-art on pay-as-you-throw and bonus-for-participation systems, both in terms of concepts and applicable models. Additionally, it will provide an updated inventory of Spanish local authorities with implementations and practical examples of their application. The project will also analyse the costs and revenues to be considered when designing pay-as-you-throw waste fees and bonus-for-participation schemes. Finally, it will present the barriers and challenges for their deployment.