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Berlin has imposed its first binding administrative fine for excessive rent in many years, reviving an enforcement tool long considered obsolete and exposing landlords in tight urban markets to renewed regulatory risk. The case turns a once-theoretical legal hazard into a tangible financial one.
The Friedrichshain-Kreuzberg district fined a landlady nearly €50,000 in October for renting a 38.5-square-metre flat at almost three times the local comparative rent. The penalty comprised a €26,253 fine plus €22,264 in repayments. The landlady withdrew her appeal a day before the court hearing, making the decision binding while avoiding a ruling that might have set jurisprudence.
Deputy district mayor Regine Sommer-Wetter, responsible for citizen services, called it "a good day for the tenants of Friedrichshain-Kreuzberg" and said she hoped the decision would serve as a model for other districts. For Berlin’s tenants and for investors, it marks the return of Mietwucher to active enforcement.
Under §5 of the 1954 Economic Offences Act (WiStrG), districts can fine landlords who charge "unreasonably" high rents during a housing shortage, typically more than 20% above the local rent index. Criminal prosecution for Wucher (usury) follows when rents exceed roughly 50% and exploitation can be proven. Administrative fines fall to local housing offices, while criminal cases go to prosecutors.
A 2004 Federal Court of Justice ruling raised the evidentiary bar, requiring proof that landlords recognised and exploited a tenant’s lack of alternatives. The result was a two-decade freeze on prosecutions.
Frankfurt am Main showed between 2020 and 2022 that enforcement remains possible. The city processed 1,384 cases, levying €321,000 in fines and securing €419,000 in repayments. The fines were modest compared with Berlin’s but proved the concept.
Friedrichshain-Kreuzberg has followed suit, appointing staff to work through a backlog despite limited resources and no digital case-management system. Other districts are watching closely.
Data from Die Linke’s Mietwucher app, launched in November 2024, indicate widespread breaches of rent limits. More than 220,000 tenants nationwide have used the app to check rents; in Berlin, 80,000 households participated. Over 70% of checks showed rents at least 20% above the legal threshold, with an average excess of 54.7% above the rent index. Nearly 3,200 cases have been formally reported to district housing offices.
These figures are self-reported and depend on user accuracy, but even with caution they suggest large-scale exposure. Die Linke estimates that correcting all reported rents to legal levels would save Berlin tenants over €200 million annually. The app now covers 14 cities, including Munich, Hamburg, Leipzig, Bochum and Erfurt.
On 6 November the Bundestag rejected a bill to strengthen enforcement, voting 440 to 131 against The Left Party’s proposal, which mirrored one already passed by the Bundesrat. It would have doubled maximum fines to €100,000 and removed the need to prove exploitation.
The governing CDU/CSU-SPD coalition opposed it. SPD parliamentary leader Matthias Miersch said his party shared "the desire to limit soaring rents" but insisted coalition discipline required waiting for the expert group on tenancy law to deliver its recommendations. The Bundesrat draft also includes a transitional clause applying only to new leases, a key point for investors assessing exposure.
The government’s expert group is due to report by end-2026. Industry observers see the two-year horizon as a holding tactic, given that the Bundesrat text, backed even by CSU-ruled Bavaria, already provides a legislative template. The delay offers little comfort to landlords facing revived district-level enforcement.
Local action is advancing faster than national reform. Frankfurt proved fines can be collected under existing law, and Berlin’s binding case gives that precedent political force. For municipalities, the model is straightforward: assign staff, process complaints, and impose penalties. The deterrent effect outweighs the cost.
Vonovia’s experience underscores the shift. In September, Berlin courts rejected its rent increases based on "quality-of-living features" such as transport links and local amenities, ruling these factors are already captured in the rent index. For listed landlords, that narrows the legal scope for further rent uplift in saturated markets.
Meanwhile, The Left Party (Die Linke) is pressing its advantage with a nationwide campaign, "Secure housing instead of rent rip-offs", staging tenant meetings in more than 80 locations and expanding its advisory network. Its language about "criminal landlords" and a "rent mafia" is hyperbolic but politically effective, and it aims to push municipalities into enforcement even without federal backing.
Berlin’s arithmetic is sobering. If its 3,200 current complaints yield even a fraction of Frankfurt’s ratio of fines to cases, millions of euros could change hands without any new law. Housing offices are becoming the front line of enforcement long before the expert group reports.
Regulatory risk in German residential property is decentralising. Instead of waiting for federal intervention, city administrations can act directly under the WiStrG. The real constraints are capacity and political will, not legality.
Institutional investors need to be aware of the following. Enforcement risk has moved from the abstract to the operational. Fines and repayment orders can hit cash flow well before any statutory change. Due-diligence now requires Mietspiegel variance checks, tenant-selection records, and scrutiny of furnished or short-term arrangements. Listed vehicles, meanwhile, face headline risk from any perception of profiteering.
Frankfurt proved the system works. Berlin has confirmed it. Other cities already have the administrative framework to follow. The Mietwucher law, long treated as a relic, is back in play, and the market can no longer price it at zero.
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