Nettomiete, Bruttomiete, Warmmiete
Nettomiete (Hauptmietzins) is the bare rent. Bruttomiete, gross rent, is net rent plus running costs (Betriebskosten) and VAT, and it is the price most ads show, often as "Gesamtmiete". Warmmiete also includes heating and hot water. Whether heating is in, the ad says; if not, it comes on top. Running costs in Vienna typically add around 2 to 4 euros per m². Compare flats by gross rent and ask whether heating is included.
Befristung (fixed-term lease)
Most rental contracts in Vienna are fixed-term. For flats covered by the Tenancy Act (Mietrechtsgesetz) the minimum term is five years if the landlord is a business and three years if it is a private person (since 2026); a shorter term is not valid as a fixed term. As a tenant you can usually end a fixed-term lease after one year with three months' notice.
Shorter terms are legal for some flats (for example in owner-occupied single-family houses), so a short term is not always unlawful, but it is always worth asking about.
Ablöse (key money)
Ablöse is money for things left behind: a kitchen, furniture, or simply 'the key'. Paying a fair price for a kitchen you take over is fine; paying for nothing is not allowed for most flats and can be reclaimed. If the price looks high, ask for an itemised list and keep the receipt.
Provision (broker commission)
Since 1 July 2023 the 'orderer principle' applies to rentals: whoever hired the estate agent pays the commission, which is almost always the landlord. If a tenant is asked to pay, the agent usually has to show that the tenant hired them first.
Kaution (deposit)
Up to three gross monthly rents is customary. The landlord must keep it in an interest-bearing account and return it with interest after you move out, minus justified costs. Transfer it only after you have signed the contract.
Richtwert, Altbau and Wohn-Ticket
For many old buildings (Altbau, built before 1945) rent is capped by the Richtwert system. If you think you pay too much, the Schlichtungsstelle or Mieterhilfe Wien check it for free. Municipal and subsidised flats need a Wiener Wohn-Ticket; ads that require one are flagged by FlatDrop.