As in teaching other languages, the most difficult of the four basic skills in teaching Turkish as a foreign language is writing; it includes very different strategies from sequencing to analysis and synthesis. In addition, foreign language learners tend to transfer the forms and meanings of their own culture and language to the target language and culture. Transfer means mutual benefit to be taken from their mother tongue as well as the other language(s) at the students' disposal and it can be observed more in bilingual or multilingual individuals. In this sense, interfering negative transfer is a type of transfer that can exhibit itself as words, affixes/suffixes and syntax, while bilingual or multilingual individuals learn Turkish. The primary purpose of this study is to identify the mistakes caused by interfering negative transfers, show the effect of multilingualism on students, and help the instructors of Turkish as a foreign language. The study group consisted of 115 Moroccan students at the level of A1-A2 who learnt Turkish in the second and third course period of the 2021-2022 academic year at the ULUTÖMER language teaching center of Bursa Uludag University. The writing skills course papers of these students at the A1-A2 level the end-of-course exam were chosen as samples. The research model was qualitatively patterned, and the research data were obtained through document analysis. The writing skills course examples included in the study were examined using the scanning technique. As far as the goals of this study are concerned, it was found that the participant students benefited from their mother tongue as well as the other languages at their disposal in their writing skills the end-of-course exam papers. The writing skills of the end-of-course exam paper of the students were evaluated within the framework of the titles of words, affixes/suffixes and syntax. This study is significant in the sense that it reveals which languages at their disposal the Moroccan students benefit from when they use Turkish in their writing skills course. After identifying the interfering negative effects of the languages that the students knew over the target language, suggestions were offered about how to eliminate those negative effects.