Under the new EU rules, all packages valued at 150 EUR or less sent under the IOSS system will need to have VAT prepaid (which should be done at the point of sale). If you are sending your package with Australia Post, your business or marketplace will need to supply your IOSS number as AusPost will be your customs declarant.
Your package will also need to have a customs VAT reference number on the parcel so it can be identified at EU customs and be treated as an IOSS parcel. Please note, that under the IOSS system, all goods sent under the IOSS should have VAT, formal clearance, and customs clearance fees applied at the point of sale. This total value should not exceed the maximum 150 EUR threshold. For more information about Australia Post IOSS numbers and how to submit your IOSS number to your customs declarant (AusPost), contact AusPost directly via their website.