A general model for cross-border exchange of information can only be built if the Once Only architecture (OOP) reffered to in the SDG regulation is considered in the work. To ensure that no additional investements are needed, we need to launch the assesment and testing of the OOP architecture, and prepare recommendations and good practices for exchange of information between Nordic and Baltic countries. The work will be devided into three phases. In the first phase, a report on the procedures listed in SDGR Annex II will be complied to find out the challenges they pose for the participating countries. In the second phase, the Proof of Concept-Pilots are chosen based on the challenge map created in the first phas, and an evaluation on the legal amendments is made. In the third phase the Proof of Concept-pilots will be implemented. As a result. we verify the OOP architecture proposed by the European Commission, identify any challenges and report on them .