Supporting academics' initial development as university teachers is important for improving their ability to contribute to high-quality education and for reducing anxiety and stress around teaching. Focusing on tasks experienced as challenging is considered a key principle for organising effective teacher professional development. To apply this principle in practice, more knowledge is needed about the development of novice university teachers' self-efficacy in their teacher tasks. Therefore, this study aims to investigate phases in the development of novice university teachers' self-efficacy. Data were collected amongst 201 novice university teachers at a Dutch research-intensive university and associated university medical centre, using a questionnaire measuring self-efficacy in different teacher tasks. Polytomous Rasch analyses were performed on novice university teachers' self-efficacy scores, both across and within teacher tasks. Results suggested three developmental phases in novice university teachers' self-efficacy across teacher tasks: (1) development in 'teaching and supporting learning', (2) development in 'assessment and feedback' and 'educational design', (3) development in 'educational leadership and management' and 'educational scholarship and research'. Two or three phases for the development of self-efficacy were found within each of these teacher tasks. These results expand our knowledge of the development of academics' self-efficacy related to specific teacher tasks. They also provide suggestions for how pedagogic training and workplace learning may be shaped in such a way that they focus novice university teachers' learning on teacher tasks that are difficult but not overchallenging.