We examined the online processing of nominal case morphology in Korean by native speakers and second language (L2) learners by contrasting canonical (SOV) and scrambled (OSV) structures, across auditory (Experiment 1) and written (Experiment 2) format. Moreover, we compared different instances of nominal case marking: accusative (NOM-ACC) and dative (NOM-DAT). During auditory processing, Koreans showed incremental processing based on case information, with no effect of scrambling or specific case marking. In contrast, the L2 group showed no evidence of predictive processing and was negatively impacted by scrambling, especially for the accusative. During reading, both Koreans and the L2 group showed a cost of scrambling on first pass reading times, specifically for the dative. Last, L2 learners showed better comprehension for scrambled dative than accusative structures across formats. The current set of results provides a complete and complex picture of the factors that affect the online processing of nominal case morphology.