A long and bureaucratic decision procedure in Spain, managed by the central government, has finally taken an end thanks to the introduction of a new law, the national "Law 7/2022 on waste and contaminated soils for a circular economy". The first good practice of the Interreg Europe INERTWASTE project explains how this legislation, transposing the EU Directive 2018/851, simplifies the valorisation process by shifting management to regional authorities who can now evaluate and approve by-product declarations. Under the new law, communication between public authorities and companies is more fluid with significantly shorter decision procedures. The submission process is simpler, and e-mail is being used at regional level, avoiding the delays caused by former tools, which involved multiple agencies. The new law also introduces the concept of "by-product". Behind the good practice is INERTWASTE lead partner and ACR+ member, Government of Navarra. The declaration of by-product of stone wool scraps is the first one it successfully approved. This may encourage other companies to follow the example and look for ways to valorise materials that would otherwise be considered “waste”, many of which go to landfill disposal.