Updated : 09/07/2014
If you have your principal residence in Austria, you can drive your car/trailer on foreign plates for one month.
The one-month period starts when you import the car into Austria and may be extended by one extra month if you can prove it was impossible to register within the first month. No additional extension is possible.
Once these periods have expired the registration certificate and the foreign number plates are to be turned in either to the in your region or to your [Bezirkshauptmannschaft]. You must now use Austrian number plates, for which registration is required.