Step 1: Which rule applies to your flat?
What matters is when the building was built and what kind it is. There are exceptions, for example for later attic conversions:
- A rented flat in an old building built before 9 May 1945, rented from 1 March 1994: usually a Richtwert rent, capped by law.
- A Kategorie D flat, meaning without a toilet or water inside the flat: a fixed, very low maximum.
- An unsubsidised new building (building permit after 30 June 1953) or an owner-occupied flat in a building from after 1945: free rent, no legal upper limit.
- Council and cooperative flats: their own rent rules; ask Wiener Wohnen or your cooperative.
- Single- and two-family houses and holiday flats: entirely outside the Tenancy Act.
Step 2: Recompute the Richtwert rent
Vienna's Richtwert has been €6.74 per m² per month since 1 April 2026. That is the starting value for an average Kategorie A flat, not yet the allowed rent. Surcharges are added, for example for a lift, a balcony, a building in good condition or an above-average location, and discounts taken off, for example for Kategorie B or C, poor condition or no cellar compartment. What counts is the state when the contract was signed.
The City of Vienna and the Mieterhilfe offer free rent calculators (Mietenrechner) for this. Compare only the base rent (Hauptmietzins), without service charges, heating and VAT.
Step 3: The most common errors in the contract
These points make an old-building rent too high most often:
- A location surcharge (Lagezuschlag) without reasons: it is only allowed for an above-average location, and the landlord must announce it in writing with reasons when the contract is signed at the latest.
- A location surcharge in a Gründerzeit area: in areas with buildings mostly from 1870 to 1917 it is in principle not allowed.
- A missing fixed-term discount: with a fixed-term contract the Richtwert rent must be 25 % lower, however long the term.
- Surcharges for features that did not exist when the tenancy started.
- Index rises above what the rent cap (Mietpreisbremse) has allowed since 2026.
Step 4: Have it checked and get your money back
First get free advice from the City of Vienna's Mieterhilfe (01 4000 8000). Then file a written application to have the base rent checked with the arbitration board for housing matters (Schlichtungsstelle, MA 50), also online. The procedure there is free and you don't need a lawyer. If several people signed the lease, you must apply together.
If the rent is too high, the agreement only holds up to the allowed amount and you get back what you overpaid. Only if one side disagrees with the decision does the case go to the district court, where fees and often the cost of an expert report apply.
Which deadlines apply?
If you miss the deadline, you usually cannot have the rent checked any more:
- Open-ended contract: apply within three years of agreeing the rent, so usually from the start of the tenancy. You get back at most the three years before the application.
- Fixed-term contract: apply at the latest six months after the tenancy ends or becomes open-ended. You get back at most the ten years before the application.
- So on a fixed-term contract you don't have to fight during the tenancy and risk your extension.
And with a free-market rent?
Free-market rents have no legal upper limit. You can still have index rises and contract clauses checked. Whether your rent fits the market, a comparison shows: the median gross rent in Vienna is currently €22.2 per m² (as of 27 October 2026). In the rent check you enter district, size and gross rent and see where you stand against the current listings in that district.
The rent check compares with asking rents, not with the legal maximum. For an old-building flat, step 2 therefore applies: even a rent below the market average can be above the Richtwert.