In November 2019, MARCOGAZ published the assessment of methane emissions for gas transmission and distribution system operators. This document gives coherent technical guidance to gas grid operators to assess their methane emissions in accordance with a harmonized and transparent method. The principles of this methodology can also be applied to other parts of the gas value chain (i.e. upstream, LNG regasification terminals and underground gas storages). MARCOGAZ is currently collaborating with CEN to convert this document into a CEN Technical Report.