Australian birth, death and marriage records are administered at state and territory level. So it helps if you know the state or territory where the event occurred. If not, there are only six states and two territories to check.
Civil registration started on the following dates:
Australian Capital Territory - 1 January 1930
New South Wales - 1 March 1856
Northern Territory - 24 August 1870
Queensland - 1 March 1856
South Australia - 1 June 1842
Tasmania - 1 December 1838
Victoria - 1 July 1853
Western Australia - 1 September 184
Some early church records are available from state BDM registries. Also look for free sources. PROV (Public Record Office Victoria) holds some early church records. You can register, order the records, visit PROV, view the records and copy them for free. I also offer lookups at PROV for a small fee.
BDM certificates and church records
The amount of information in records and indexes varies widely between the states and territories, and it has changed over time. Church records generally contain much less information.
Access to historical certificates also varies. Waiting periods can be up to 100 years for birth, up to 30 years for death and up to 75 years for marriage records.
Where uncertified images are available, this is a worthwhile option for family historians. Uncertified images are cheaper but contain the same information. Certified images are only required for legal purposes.
Australian BDM registrars
Australian Capital Territory Registry of Births Deaths and Marriages New South Wales Registry of Births Deaths and Marriages Northern Territory Registry of Births Deaths and Marriages Queensland Registry of Births Deaths and Marriages South Australia Births Deaths and Marriages Registration Office Tasmanian Registry of Births Deaths and Marriages Victorian Registry of Births Deaths and Marriages Western Australian Registry of Births Deaths and Marriages