The adaptive optics module of MAVIS will feed an imager and spectrograph with an MCAO corrected wavefront, producing near-diffraction-limited science in the visible spectrum over a wide field of view. To capitalise on this performance, non-common path aberrations between the wavefront sensors and science instruments must be measured and corrected over the field. Additionally, there will always be a small amount of undesirable distortions over the field of view induced by optical surfaces and imperfections, which must be characterised to deliver the required astrometric performance in MAVIS. We describe the methods proposed for both the NCPA and astrometric calibrations, as well as the status of their early development.