This study investigates the challenges faced by English teachers in designing lesson plans under two distinct Indonesian curricula: Kurikulum 2013 and Kurikulum Merdeka. Employing qualitative methods through interviews with teachers at MAN 1 Banda Aceh, the research reveals significant differences between the two curricula. Kurikulum 2013 is characterized by its structured framework, which often restricts teachers' creativity and adaptability. In contrast, Kurikulum Merdeka provides greater flexibility, emphasizing student-centered learning and interactive methods that enhance classroom engagement. Despite these benefits, teachers encounter obstacles such as time constraints, ambiguous learning objectives, and limited teaching resources when implementing both curricula. The findings highlight the importance of comprehensive training and institutional support to equip educators with the skills and resources necessary for effective curriculum implementation. This study contributes valuable insights into curriculum development and offers practical recommendations for improving English language instruction in Indonesia. It underscores the need for balancing structure and flexibility in lesson planning to meet diverse educational demands while fostering teacher innovation and student engagement