In particular, the new Act:

• includes simplified outlines to assist readers to understand the new Act
• sets out the circumstances in which people automatically become Australian citizens
• sets out the eligibility requirements for the acquisition of Australian citizenship by descent, adoption, conferral or resumption
• changes the residence requirement for most citizenship applicants to four years lawful residence immediately before making an application
• allows the permanent resident spouse or interdependent partner of Australian citizens to have their residence outside Australia taken to be residence in Australia in certain circumstances
• provides for the acquisition of citizenship by people born in Papua prior to 1975 to an Australian citizen parent born in Australia as currently defined
• allows children who were born after a parent ceased being an Australian citizen upon acquiring the citizenship of another country to become Australian citizens
• prohibits the approval of citizenship for people, other than certain stateless people, who are assessed as being a risk to Australia's security
• prohibits the approval of citizenship for certain stateless people who have been convicted of national security offences or other offences for which a sentence of imprisonment of at least five years has been imposed
• prohibits approval of citizenship by conferral during any period in which there is pending action that could be taken in respect of the person under a law of the Commonwealth, a State or Territory, any periods in prison and certain periods following imprisonment
• removes the age limit for former Australian citizens, who renounced their citizenship to become citizens of another country to avoid suffering significant hardship or disadvantage, to resume Australian citizenship
• provides for the collection, use, storage and destruction of personal identifiers
• extends the provisions for revocation of Australian citizenship to include serious criminal offences committed at any time prior to acquisition of citizenship, and third party fraud
  and
• provides the discretion to revoke a child's citizenship if the child's only Australian citizen responsible parent ceases to be an Australian citizen.

Detailed information can be found on the Citizenship website.
See: www.citizenship.gov.au