The Australian Business Number (ABN) is a single identifier for all business dealings with the tax office and for dealings with other government departments and agencies. Provides links to relevant forms.

http://www.ato.gov.au...

http://www.ato.gov.au/Businesses/pathway.asp?pc=001/003/021

ABN Lookup provides access to the publicly available information provided by businesses when they register for an Australian Business Number (ABN).

http://www.abr.business.gov.au...

http://www.abr.business.gov.au/

The Australian Business Register allows you to apply for Australian Business Number (ABN), Business tax file number (TFN), Good and Services (GST)/Fuel tax credit, and Pay As You Go (PAYG) Withholding. You need to read the ABR's privacy policy before entering a secure transaction.

http://www.abr.gov.au...

http://www.abr.gov.au