The Map task corpus of heritage Bosnian/Croatian/Montenegrin/Serbian (BCMS) consists of elicited conversations (map tasks) by 29 second-generation BCMS speakers originating from different regions of former Yugoslavia and living in German-speaking Switzerland. The corpus is suited for researchers of heritage BCMS, as well as students and teachers of BCMS living in diaspora. The corpus contains 30 turn-aligned transcripts with an average length of 6 minutes. The texts are annotated with the CLASSLA pipeline (https://github.com/clarinsi/classla) on the levels lemmatisation, MULTEXT-East Version 6 morphosyntactic descriptions, Universal Dependencies part-of-spech and morphological features. The corpus is enriched with corpus-specific annotations of truncations, elongations, stutter and code-switches. It is distributed in source TEI and derived vertical formats.