Data Transmission Monitoring tool (DTMT) is an online platform designed to facilitate exchange of information among the end users of data, Member States (MS) and Commission. The objective is to efficiently monitor and communicate data issues and in the long term improve the flow and quality of data. The Guidance document for the DTMT has been developed in stages under the guidance of DGMARE, JRC and STECF at the STECF Plenaries and it was last updated and endorsed by STECF Plenary in March 2023. The DTMT Guidance document is intended to be a living document and updated no more than once a year.