For most courses, it’s on the basis of UCAT results (e.g. UQ, Griffith, CQU, Adelaide, Newcastle & UNE, WSU & CSU) or UCAT combined with academic results (e.g. CSU, UNSW, Curtin, Monash).
This means that if you want to have the best chances of getting an interview, your UCAT score needs to be as high as possible. The minimum UCAT threshold for receiving an interview offer changes every year (since it depends on how applicants perform that year), and it’s never released until after the UCAT exam, if it’s released at all.
In 2020, the general minimum cut-off for medical schools that only consider UCAT when making interview offers was 93rd percentile, while a ‘safe’ UCAT mark for scoring an interview was around 95th percentile, based on the numbers reported by around 1,300 iCanMed students. Compared to 2019, this was a massive jump in the minimum required score, which is why the higher your UCAT score is, the better. For medical schools that consider both UCAT and ATAR when making interview offers, a very high ATAR can help to offset a slightly lower UCAT score (more information on this in this article), but only to an extent.
You can find a full breakdown of how candidates are screened for interview offers for each program in the entry criteria.