Anybody who wants to become an Australian citizen needs to make a formal application, and the time it takes for the process to take place can vary. Usually it takes between three and six months for a decision to be made on an application, but if you need to take part in a citizenship ceremony you may have to wait for another six months.
In brief, the application process will begin with you determining what type of application suits your particular circumstances. As a migrant in Australia, you need to have a permanent residence, which satisfies particular requirements, and you need to be able to show that you are of good character. If you have children under the age of 16 who you want to include in your citizenship application, they also have to be residing permanently in Australia. You will know if you have been granted permanent residence by the type of visa that you hold; if it allows you to remain in Australia indefinitely, you are eligible to apply for citizenship.
You will need to have original documents to prove your identity, and that will support your eligibility to become an Australian citizen. These documents must show your photograph, signature, current residential address and your date of birth and all names that you have been known by. As a migrant, you will also need to provide evidence of when you arrived in Australia.
You will have to submit the relevant fee with your application. These fees vary depending upon your circumstances and whether you are eligible for any concessions. You can find all the information that you need regarding the fees (which are stated in Australian dollars - AUD) and any other information that you need about Australian citizenship on this site: www.citizenship.gov.au/ A migrant becomes an Australian either when they get a Permanent Residency status. As per most immigration visa's after 2 years. I bit like a skilled migration visa. After 2 - 4 years person can become an Australian Citizen by showing their intent to continue living in Australia