Because of the active credit reporting process which generates your credit file in Australia, borrowers should be aware that there is no benefit in not fully disclosing all existing credit contracts when applying for a loan.
Usually when you apply for a home loan, your lender will ask you to confirm the outcome of your historic credit applications based on what they see in your credit file. If they are not satisfied with your response, under the terms of the privacy document you would have signed, they may seek confirmation directly with each credit provider noted on your credit file.
Your ability to repay a new loan is determined not just by your income but also by your liabilities. If a lender has reason to suspect that you have additional undisclosed borrowings that would obviously impact on your ability to repay the new loan, then they will fully investigate this to ensure they do not breach any legislative requirement to ensure that the loan they are recommending is not unsuitable. The existence of your credit file should motivate you for full disclosure.