One‑stop public services and single window systems are primary goals of many e‑government initiatives. How to facilitate the technical and data interoperability among the systems in different government agencies is a key of meeting these goals. While many software standards, such as Web Services and ebXML, have been formulated to address the interoperability between different technical platforms, the data interoperability problem remains to be a big challenge. The data interoperability concerns how different parties agree on what information to exchange, and the definition and representation of such information. To address this problem, the Hong Kong government has released the XML Schema Design and Management Guide as well as the Registry of Data Standards under its e‑Government Interoperability Framework initiative. This paper introduces how the data modelling methodology provided by the Guide can be used to develop data interfaces and standards for e‑government systems. We also discuss how the Macao government has formulated their data interoperability policy and has applied the Guide in their situation.