Accurate taxonomic knowledge and tools are needed to understand the drivers and impact of biodiversity decline. However, the field of taxonomy is severely hampered by a continuous decrease in capacity. With TETTRIs, we envision a transformative change in the field of taxonomy to build and sustain taxonomic research capacity through increasing knowledge and developing systems. TETTRIs will achieve this aim by creating joint knowledge in reference collections, training frameworks, and with innovative tools as well as by developing centralized resources providing access to an expertise marketplace, the taxonomic knowledge platform, and career paths. The core methodology for reaching these objectives includes co-creation with citizen scientists, and professionals in biodiversity hotspots. The open-access knowledge and systems built into TETTRIs, together with citizen scientists, will accelerate the integration and expansion of taxonomy in education, governance, and multidisciplinary research. This will ensure the long-term relevance of taxonomy as an instrumental science, necessary to halt European and global biodiversity loss, and ensuring ecosystems and their services are preserved and sustainably restored on land, inland water and at sea. TETTRIs builds taxonomic research capacity near biodiversity hotspots by networking natural history museums and other taxonomic facilities through bottom-up co-creation between 17 partners. The consortium includes the European Citizen Science Association and several of Europe's leading natural history museums, botanic gardens and universities unified under CETAF, the leading European voice for taxonomy and systematic biology. Impact throughout the EU and beyond is secured through involvement of associated initiatives such as DiSSCo and DEST, partners in third party projects, and key TETTRIs dissemination activities towards a new generation of taxonomists, citizen scientists, users in need of taxonomic knowledge, and decision makers