This technical note describes a method for determining whether and to what extent Parties to the Paris Agreement have enhanced their nationally determined contributions (NDCs) with respect to greenhouse gas (GHG) mitigation. We estimate each Party’s target-year GHG emissions under its previous NDC (typically First NDC) and under its subsequent NDC (typically Updated First NDC or Second NDC). On this basis, we determine whether the subsequent NDC reduces emissions relative to the previous NDC and—where possible—by how much. We outline approaches for NDCs with GHG reduction targets and with non-GHG targets and policies.