No matter what visa subclass you are applying for, if the Department wants more information from you they will issue an information request, also commonly referred to as a 28 day notice.
You will receive two documents, the formal request and a document checklist detailing the material/information to be supplied.
We have recently had feedback from Applicants, self-managing their applications, the Department would not assist them when seeking clarification of the request received. In general terms (there are exceptions) the Department
Once the time line to answer the request has expired the Department can make a decision on the application without further referral to you.
If you need more time to respond to a request make a formal request in writing to the case officer seeking an extension of time. Detail your reasons for the extension and if possible support this is documentary evidence (e.g. a written responses from a third parties setting out a time line to provide documents requested).
It is important to remember that even if the 28 days has expired the Department is obligated to consider all information provided prior to making a decision on your application. So even after the 28 days the case officer must consider information provided.
Whilst most information requests are for a 28 day period, some requests under various parts of the legislation give you shorter time periods. Read your request carefully.