Americans are required to have a valid U.S. passport when entering Austria. The passport must have a remaining three-month validity before expiration or at least a period of remaining validity that coincides with the return ticket. There should also be at least one blank page available in the passport for entry and exit stamps.
Americans are only permitted to stay in Austria without a visa for up to 90 days. If after the 90 days you need to extend your stay for a justifiable reason, you can apply for a 90-day extension at an Austrian Federal Police Station. It is up to the interviewing officer to grant or deny your extension. All extensions must be applied for before the initial 90 days have expired.
Americans planning to stay in Austria for a period of three to six months must obtain an entry permit from the Austrian Embassy or Consulate General in the United States. If you intend to partake in business, pleasure, study or volunteer work exceeding three months, you must apply for a Schengen Visa by submitting an application form, document evidence and the applicable fee to the Austrian Consulate General servicing your state of residence.
Americans intending to stay in Austria for work, study, family affairs, retirement or other engagements for periods exceeding six months must apply for a residence permit. The residence permit must be applied for at an Austrian Consulate General in the United States before entering Austria. The application process requires various forms and documents particular to each type of (reason for) residence permit. Once the application is approved by the Consulate or Embassy, the permit must be picked up at the issuing authority inside of Austria.