The Clothing EPR (Extended Producer Responsibility) Sandbox Project, concluded in April 2024, demonstrated the potential for an intelligent variable fee system to incentivise circularity within the UK textiles and fashion industry. Led by QSA Partners with the help of UK Fashion & Textiles Association (UKFT), British Fashion Council (BFC) and British Retail Consortium (BRC) and supported by Innovate UK’s National Interdisciplinary Circular Economy Research programme (NICER), this project brought together major industry trade organisations, brands, retailers and academic experts to address key data challenges and explore the impact of circular eco-modulation. Objectives and Approach The project’s primary goals were to analyse existing producer data sets to enable circular eco-modulation and identify data gaps. The project modelled variable fee levels to demonstrate their effects without optimising eco-modulation levels. Data from over 500,000 types of garments, covering hundreds of millions of individual items, were gathered and analysed. The project achieved clear scores for over 85% of the data, applying a maximum score to the remainder where data was incomplete.