Abstract: For operating a correction service system for a satellite-based navigation system that is configured to determine a position of user devices, where the correction service system includes a plurality of reference stations having known and fixed coordinates and a plurality of receivers, a method includes operating a first group of the reference stations and the plurality of receivers, ascertaining a first correction value based on the satellite signals received by the first group of reference stations and their coordinates, ascertaining a second correction value based on the signals received by the plurality of receivers, ascertaining, based on the first and second correction values, a third correction value that is provided to the user devices.