If you are going to stay in Austria for less than six months you can apply for a Visa C (for stays of up to 90 days) or for a Visa D (for stays of from 91 days up to a maximum of 6 months) at the competent Austrian representative authority in their country of residence. These visas are free of charge.

However, if you are going to stay for less than 90 days/three months, you do not need a visa if you are entitled to enter Austria without a visa. The following documents may be required of you when getting this type of visa:

• Invitation letter or an employment contract from the Austrian company you will be visiting. The letter should contain their company name, address, accompanied by your dates and purpose of visit.
• Fully accomplished and signed Austrian Visa Type-D Application Form.
• (2) Two pieces of identical photographs that are no older than three months and taken with consideration to the ICAO Standards.
• Passport that contains at least two blank pages to be able to affix the Austrian Visa sticker. Validity of the passport should be 3 months after the date of exit from Austria or Schengen territory. The passport should be no older than 10 years as well.
• Bring copies of your previous visa are available.
• Appointment confirmation letter, to be done online through this link.
• You will also need a cover letter where you will explain further details about your visit to Austria.
• A copy of your round-trip flight itinerary.
• Schengen Travel Insurance copy of confirmation or proof of purchased insurance for travel in Austria and the whole territory of Schengen, with minimum coverage of USD 50,000.
• Accommodation receipts or hotel confirmation that will show where you will stay in Austria for the whole duration of your stay.
• Proof of civil status (may be a marriage certificate, birth certificate, or death certificate of a spouse).
• Proof of sufficient financial means that will cover your whole stay in Austria. the Austrian Immigration office requires a person to possess euros in the equivalent of USD 110 per day of stay for the entire duration of your visit.
• 6 months bank account statement

If your work will last longer than 180 days, you will need to apply for an Austria Red-White-Red Card. For more information on this type of permit, you may check out this link. 

To Apply:

• Collate all your documents and check for other relevant documents that will help prove your ability to sustain your visit to the country.
• Look for a local Visa Application service provider who can walk your documents.

If there are no service providers, you may submit to Austrian Embassies near you. For details on addresses, you may click this link here.