The supply of services by a non-resident is subject to VAT in Austria.
When a non-resident has an establishment in Austria, the establishment is required to register for and pay VAT when the registration threshold is met.
When a non-resident has no establishment in Austria, the supply of services is generally subject to reverse charge. If the supplier exclusively provides services subject to the reverse charge, they are not required to register for VAT.
If the non-resident makes supplies in Austria that are not subject to reverse charge, they are required to register for VAT regardless of meeting the registration threshold. If the supplier is resident in another EU country, they may register directly. If the supplier is resident in a non-EU country, they are required to appoint a tax representative that is resident in Austria.