The present study investigated the relationship between two different syntactic information types, namely word category and morphosyntax. The event-related brain potential (ERP) pattern of acoustically presented sentences containing two syntactic anomalies (word category and subject-verb agreement) was compared to the ERP response to sentences containing a single violation. The ERPs for the agreement violation revealed a left anterior negativity (LAN) indicating the detection of the morphosyntactic error, followed by a P600 reflecting processes of reanalysis. The ERPs for both the category and the combined violation showed an early negativity reflecting processes of phrase structure building, followed by a P600 indicating syntactic reanalysis. Additionally, a broadly distributed negativity following the early negativity and preceding the P600 was observed. This ERP component is suggested to reflect reference specification processes arising from the specific sentence structure used in the present study. The ERP pattern for the combined violation suggests no additivity or interaction between the two syntactic anomalies in the early time windows (early negativity, reference-related negativity, and LAN), whereas interactive effects are observed in a late time range (P600).