You’re legally required to keep all of your Australian business number (ABN) registration details up-to-date, including: 

• business contact details (for example, email address and phone number) 
• main business activity 
• business addresses (for example, main business address, postal address and any additional locations) 
• business associate details (for example, director, public officer, shareholder, trustee, partner). 

You need to notify the ATO of any changes to your ABN details within 28 days of you becoming aware of the change. The fastest way to update your details is through the Australian Business Register (ABR) portal; ABR online services.