If you are not a citizen of an EU/EEA country or Switzerland, then you are considered a third country national.
Entry without a visa
If you have a valid residence title of another Schengen member country or you are a national of one of the countries with a visa-free entry you do not need a visa to enter and to reside in Austria for up to 90 within 180 days.
Students who are enter Austria without requiring a visa may also have submit their application at the Austrian competent residence authority (Municipal Department 35 in Vienna). Furthermore, it may be possible to submit an application in Austria after entry with a visa that has been lawfully acquired for purposes other than the domestic application provided that the domestic application was not the (hidden) reason for the visa application (case-by-case examination).
You are not permitted to overstay your visa-free stay or the period of residence defined in your visa. It is highly recommend that you apply as soon as possible after entry.
All necessary documents have been submitted in person, the residence authority has 90 days for processing your application.
Entry with a visa
If you have submitted your application for a place at one of Austria´s universities which requires an examination for admission, this institution will issue a "conditional notification of admission" (Bedingter Zulassungsbescheid). With this conditional notification and all other necessary documents you have to apply in person for a residence permit – for students (Aufenthaltsbewilligung – Student) at the competent Austrian authority in your country of residence. Furthermore, you will have to show credibly sufficient financial means and accommodation (e.g. by a confirmation of maintenance payments by your parents, a preliminary rental contract or reservation of a room in a student residence).
You should apply for the residence permit at least three months before the date of the entrance examination. It may take several months to legalize the documents required for an application.
If the residence authority in Austria decides to grant you the residence permit, you have to apply for a Visa D at that authority to be able to enter Austria,. Visa D allows you to travel to Austria and sit the entrance examination and is valid for four months.
If you pass the entrance examination you have to submit your definite notification of admission (Zulassungsbescheid/Aufnahmebestätigung) and provide documents proving sufficient financial means and proof of accommodation to the competent authority in Austria. You have to collect your residence permit within the validity period of your visa.
If the entrance examination takes place a long time before the possible start of your studies, you may also apply for a visa C at the Austrian authority, which will be issued for the period of the examination.
In case of a positive decision, your residence permit will be issued for a period of 12 months. If you applied for a shorter term or your travel document is valid for a shorter period of time, your residence permit will be issued for that period.