Guarantees of Origin (GOs) track renewable electricity attributes across European markets via conventional book and claim, acting as Europe's dominant EAC. Producers receive one GO per megawatt-hour delivered to the grid, and issuance occurs after production data is transmitted to the respective national registry operator. Guarantees of Origin are bought and sold, and exit supply via expiry or cancellation.

GOs are regulated by EU Directive 2023/2413, (commonly known as REDIII), and are operationalised via the EECS rules (overseen by the AIB).