Australian Business Number ABN
ATO (CWLTH) resource. Rules Mate indexes this as part of the Australian compliance corpus. Click through for the regulator's primary source.
https://www.ato.gov.au/forms-and-instructions/trust-tax-return-2013-instructions/completing-the-tax-return-page-1-trust-tax-return/australian-business-number-abn
Rules Mate indexes Australian government compliance resources to make them searchable. We link to + summarise; always verify the live source before acting.