Before you enter into a contract of general insurance with an insurer, you have a duty, under the Insurance Contracts Act 1984 (Cth), to disclose to the insurer every matter that you know, or could reasonably be expected to know, is relevant to the insurer's decision whether to accept the risk of the insurance and, if so, on what terms.
You have the same duty to disclose those matters to the insurer before you renew, extend, vary or reinstate a contract of general insurance.
Your duty however does not require disclosure of matters:
that diminishes the risk to be undertaken by the insurer;
that is of common knowledge;
that your insurer knows or, in the ordinary course of its business, ought to know;
as to which compliance with your duty is waived by the insurer.
If you fail to comply with your duty of disclosure, the insurer may be entitled to reduce their liability under the contract in respect of a claim or may cancel the contract. If your non- disclosure is fraudulent, the insurer may also have the option of avoiding the contract from its beginning.