You must apply for a further extension for 3 months before your current visa becomes invalid. And if someone is planning to visit Austria for more than 90 days then he must apply for Visa D which applies to staying for more than 6 months. Worrying about an Austria extension? Here is a simple step that you need to follow.
Extension letter
Document Required To Extend an AustriaVisa
Process- Tourist Visa Offline
Travelers must understand that every country has its rules and regulations, specifications, and document requirements. If someone is planning to get a residence extension then he/she must require certain documents. The extension service for Austria visas is for people who already have valid Austria visas and wish to extend those Visas. Here is a list of complete documents that are required while applying for the extension for the Austria visa. The following documents are typically required for a visa application to Austria: