you face both criminal and civial penalties. The bank will call the loan in, you will have 30 days to repay the loan in full. You will then have to try to find a new lender - lenders frequently breach the privacy act by letting other lenders know about fraud cases - maybe it is not a breach. There are only 2 main insurers so if your loan is above 80% you are in an even worse position.
Up to 5 years prison for a charge of obtaining a financial advantage by deception. There may be other criminal charges as well.
not to mention the ato may become involved looking at the income declared and then assessing you on it.