According to the Australian Taxation Office, you can conduct any number of businesses/activities under the same ABN provided they all operate under the same business structure.
If your second or subsequent business operates under a different structure, you will need to apply for a new ABN for your virtual assistant business.
While the requirement to update your ABN if your main business activity changes has been around for a while, the ATO also recently announced that you can now include up to 4 additional business activities when you update your ABN details.
It’s important to note that Thought Penny and the VA Lead Network will never provide information that constitutes financial advice. You should seek independent advice for your unique circumstances.