The IMPACTS project has a stated broad objective to develop the knowledge base of CO2 quality required for establishing norms and regulations to ensure safe and reliable design, construction and operation of CO2 pipelines and injection equipment, and safe long-term geological storage of CO2. More specifically for this paper, the project sets out to reveal the impacts of relevant impurities in the CO2 stream on the design, operation and costs of the capture, transport and storage infrastructure and to provide recommendations for optimized CO2 quality through techno-economic assessments (amongst other considerations). This paper gives an overview of the work being carried out to investigate the impact of CO2 quality in various areas including corrosion, water content in the CO2 stream and the injection and storage processes. The paper reports on the derived impacts of the above mentioned aspects of CO2 quality. These impacts are combined with estimates of the cost of measures to mitigate or prevent these impacts from affecting the operation of the CCS system, or of adapting of CCS system design. Thus, the impacts can be set out as a set of cost functions relating to Capex and Opex and including the effects of overall availability and process efficiency changes. A specifically designed CCS chain model is used to assess the impacts on a number of reference CCS chains, carrying out comparative economic trade-offs to both understand the fullchain whole-life economics of certain CO2 impurities at different levels and then to potentially optimize a purity specification for various sets of circumstances.