Is it mandatory for a business to change their details on the ABR?

Legislation requires that the Registrar must be notified within 28 days when a change to ABN details occurs. Refer to section 14 of A New Tax System (Australian Business Number) Act 1999.

The following details can be changed on the Australian Business Register (ABR):

names
addresses
authorised details and associates
business details, for example, main business activity and main industry code
financial institution account details.

Changes to these details can be advised using one of the following methods:

online via the internet using the ABR if you have a digital certificate, refer to Can business clients check or change details at their convenience?
electronic lodgment service (ELS) (name, address and authorised contacts only) - applies to tax agents only
by phoning the Tax Office on 13 28 66 (the entity name cannot be changed via the telephone)
by completing a Change of Registration details form (NAT 2943) - available from the Tax Office
by sending a signed letter containing the information necessary to make the changes, or
through government agencies interacting with the ABR.

You must be recorded with the Tax Office as being authorised to make changes or update details on behalf of the entity. In all cases, proof of identity (POI) must be established before any updates to an ABN record can be made. For further information, refer to the Proof of identity policy.