Interoperability is a major challenge in providing pan-European e-government services (PEGS) across Member State (MS) borders. Improving interoperability in PEGS is expected to increase collaboration and efficiency across public administrations. Yet, a comprehensive approach to develop interoperable PEGS is still missing. Enterprise architecture (EA) is a concept used in the private sector to deal with organisational complexity, interoperability and the multifaceted challenges of information systems. We argue that EA can be used in a similar manner to foster interoperability in PEGS. This paper elicits requirements for constructing an EA framework for PEGS. The requirements are used to argue the suitability of existing EA frameworks and to propose areas of further research to build a customised architecture framework for ensuring interoperability in the design and implementation of PEGS.