A crucial question in the development of a new climate change agreement centres on the “intended nationally determined contributions” (INDCs) that parties have agreed to communicate before the COP 21 in Paris in December 2015. This paper explores options for the design, organization and timing of the ex ante assessment process of the INDCs. It identifies key choices to be made in Lima, and the implications of these choices for the road to Paris. Finally, it discusses the implications of the design, organization and timing of the assessment for future review processes under a Paris agreement.