This paper synthesizes key lessons learned from an assessment of the first 14 applications of carbon-offsetting programs for eligibility under CORSIA. The evaluation shows that the degree to which the applicants satisfy the ICAO requirements differs substantially. The authors recommend that ICAO clarifies several key matters for environmental integrity in the operationalization of its requirements and that it only approves programmes as soon as they fulfil all criteria, following a transparent review procedure. Furthermore, authors recommend that the Parties to the Paris Agreement include specific provisions in the international rules on Article 6 for how countries should account for offset credits used under CORSIA.