In Finland, there are free nationwide reference systems, EUREF-FIN coordinate system, N2000 height system and FOGN gravity system. On top of these there is a national geoid model FIN2005N00 that is a transformation surface between EUREF-FIN and N2000 heights. Today these national reference systems are static i.e. their fixed numerical values define the systems. However, movements of the ground caused by the land uplift and continental plate motion weaken the accuracy of the systems. We need to find research-based solutions that guarantee accurate enough reference systems for every application. In this project, we research some aspects that support decision making when future reference systems are to be created. Research questions are:

• Are uplift models and results from European Adjustment (EVRF) usable for maintaining the height reference frame?
• What is the agreement level of the coordinates between current definition and active definition of coordinate reference systems?
• What are the requirements if we change into active definition of coordinate reference system?
• What is the relative accuracy between two points when using current official geoid model?
• Is it possible to get more accurate transformation surface between EUREF-FIN and N2000 using more current geoid solutions?