Five years minimum (three for private landlords)
Since 1 January 2026, a fixed term on a flat under the Austrian Tenancy Act (Mietrechtsgesetz), which covers most rentals in Vienna, must run at least five years if the landlord is a business, such as a property company or a professional landlord. Private landlords can still agree three years, and contracts signed before 2026 keep the old three-year minimum. The term must be agreed in writing. A shorter term is not valid as a fixed term: the lease then counts as unlimited.
There are exceptions, for example in single-family houses or some owner-occupied buildings, so a short term is not automatically illegal. If in doubt, Mieterhilfe Wien checks it for free.
Ending early
You can end a fixed-term lease after the first year with three months' notice to the end of a month, in writing. The landlord can't end it early except for serious reasons such as unpaid rent.
When the term runs out
If nobody ends the lease and you simply stay, it is extended once, by five years (three if the landlord is a private person). If it runs on after that too, it becomes an unlimited lease. Get any extension in writing.
Fixed-term should mean cheaper
In old buildings under the Richtwert system the rent for a fixed-term lease must be 25% below the permitted unlimited rent. If you think the discount is missing, the Schlichtungsstelle can check it.
FlatDrop flags short or unstated fixed terms in every alert, and its AI score takes the term into account, so a one-year sublet never looks as good as a long lease.