Your Return of Service Obligation
So how long do you need to serve in the ADF if you're successful in your application?
Typically, there are early points during your basic training when you can decide that military service is not for you and you can leave. However, after a certain point, the ADF have invested so much into your training there is an expectation (backed by policy) that you will serve a minimum period of time (like a prison sentence - only kidding!)
The length of service required is called your ROSO (Return of Service Obligation). This is pronounced [Rozzo]. This exists because it is extremely expensive to recruit, train and develop military personnel. So if people left after a couple of years, it becomes extremely expensive to maintain the personnel costs.
The actual length of service required depends on the position. Typically, the longer the training you receive the longer the ROSO. In fact, your ROSO can even be extended mid-career following certain training courses. For example, in my own career, I completed a year of intensive language training at the ADF School of Languages. This resulted in an additional two years of service being added to my ROSO (After all, I was paid my full time pay to be a student for 12 months including overseas placement training!)
In most cases your ROSO is at least four years and for officer training it is usually at least six years if not more. The exact ROSO depends on the position.
A word of caution if you're asking about the ROSO in your interviews. The recruitment staff may be wary of your question if you are indicating you are only looking for a short term career. Of course, you're entitled to leave at the end of your ROSO, however, if you are competing with other applicants who state they are looking for a long term career you can understand that you may come off second best.
It is still reasonable to ask about the ROSO on the basis that you want to have full understanding of your obligations and commitments to the ADF. You can still be in it for the long term, but there is no reason to be ignorant of the minimum length of service for your preferred service or position.