The issues here are fraud and false documents (forgery).
While the mere possession of false documents is not necessarily a crime, the use of false documents in order to obtain a financial advantage is fraud, which is a crime defined by statute in all states. States may also have specific provisions relating to the possession of falsified documents, but generally it is not criminal unless the possessor is aware it is a false document, and that it will be used to secure some advantage.
Fraud
For example the Crimes Act 1900 (NSW) s192E states:
(1) A person who, by any deception, dishonestly:
(a) obtains property belonging to another, or
(b) obtains any financial advantage or causes any financial disadvantage,
is guilty of the offence of fraud.
Forgery
Additionally, s253 of the same Act states:
A person who makes a false document with the intention that the person or another will use it:
(a) to induce some person to accept it as genuine, and
(b) because of its being accepted as genuine:
(i) to obtain any property belonging to another, or
(ii) to obtain any financial advantage or cause any financial disadvantage, or
(iii) to influence the exercise of a public duty,
is guilty of the offence of forgery.
Maximum penalty: Imprisonment for 10 years.
... and s255 (also see s254, which contains very similar provisions for the actual use of false documents):
A person who has in his or her possession a false document, knowing that it is false, with the intention that the person or another will use it:
(a) to induce some person to accept it as genuine, and
(b) because of its being accepted as genuine:
(i) to obtain any property belonging to another, or
(ii) to obtain any financial advantage or cause any financial disadvantage, or
(iii) to influence the exercise of a public duty,
is guilty of an offence.
Maximum penalty: Imprisonment for 10 years.
... and s307C:
(1) A person is guilty of an offence if:
(a) the person produces a document to another person, and
(b) the person does so knowing that the document is false or misleading, and
(c) the document is produced in compliance or purported compliance with a law of the State.
Maximum penalty: Imprisonment for 2 years, or a fine of 200 penalty units, or both.
(2) Subsection (1) does not apply if the document is not false or misleading in a material particular.
(3) Subsection (1) does not apply to a person who produces a document if the document is accompanied by a written statement signed by the person or, in the case of a body corporate, by a competent officer of the body corporate:
(a) stating that the document is, to the knowledge of the first-mentioned person, false or misleading in a material particular, and
(b) setting out, or referring to, the material particular in which the document is, to the knowledge of the first-mentioned person, false or misleading.
(4) The burden of establishing a matter referred to in subsection (2) or (3) lies on the accused person.
