There is a need to calculate GST on Purchases made from Foreign Vendors. The Foreign Vendors will not have ABN but ARN (ATO Reference No.) and are registered with ATO under ‘Simplified GST Registration’. GST credit cannot be claimed against these transactions.
In the current design, ABN field in the Vendor card cannot accommodate ARN. The logic for ARN is different from that of ABN and does not meet the validation setup for ABN in the Vendor card. So there is a need to accommodate ARN in the Vendor card for these Vendors so that they can lodge GST returns and pay GST quarterly and can pay electronically via SWIFT, bank transfer, credit or debit card.

Please refer to the below link:

The expectation is to enter ARN for Foreign Vendors in the Vendor Card.
Currently the feature is missing in Business Central - Australia localization.
Needs Votes
Ideas Administrator

Thank you for this suggestion! Currently this is not on our roadmap. We are tracking this idea and if it gathers more votes and comments we will consider it in the future. Best regards, Business Central Team