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The Mietpreisbremse is reshaping the German rental market
Germany's residential rental market ended 2025 with an awkward contradiction at its core. After a decade of rent control, advertised rents are rising faster than inflation. At the same time, supply is shifting towards segments that increasingly bypass the very regulation designed to contain prices. The latest GREIX Rental Price Index provides the clearest evidence yet that the Mietpreisbremse is reshaping the market rather than stabilising it.
According to Q4 2025 GREIX data from the Kiel Institute, asking rents across 37 German cities rose 4.5% year on year, roughly twice the rate of general inflation. Quarter on quarter, rents increased by 1.0%, equivalent to a real rise of 0.7%. What makes these figures significant is their timing: they come after ten years of nationwide rent control and amid a sharp contraction in advertised supply.
Rental listings fell 7% year on year and now stand around 20% below 2015 levels. Fewer apartments are reaching the market, and those that do are priced higher. As Jonas Zdrzalek, GREIX project leader, puts it, tenants face "difficult conditions": shrinking supply, rising prices and tougher contractual terms. For professional investors, the message is increasingly uncomfortable. Scarcity is no longer a temporary feature of the German rental market; it is its defining characteristic.
From rent cap to market segmentation
The most striking development in the GREIX data is not the pace of rental growth but where it is occurring. Furnished and fixed-term apartments, once a niche product, have moved firmly into the mainstream. Nationwide, more than 17% of all rental listings in 2025 fell into this category. In Germany's eight largest cities, the share approached one quarter. In Munich, it reached nearly one third.
This matters because furnished and temporary rentals sit in a regulatory grey zone. The Mietpreisbremse applies in principle, but enforcement is weak and transparency limited. The result is growing market segmentation: a tightly regulated "classic" segment with declining supply, and a loosely regulated segment where rents adjust far more freely.
Research commissioned by the Federal Construction Ministry and carried out by the Institute for Housing and the Environment alongside BBSR (Bundesinstitut für Bau-, Stadt- und Raumforschung) reinforces this picture. In cities with more than 500,000 inhabitants, more than 30% of rental advertisements at the end of 2024 were for furnished or fixed-term apartments, double the share recorded in 2012. Alexander Schürt, a housing market expert at BBSR, describes these forms of letting as "no longer a marginal phenomenon" but increasingly shaping urban housing markets.
The pricing differential is stark. Average asking rents for furnished temporary apartments rose by around 80% between 2012 and the end of 2024, reaching roughly €27 per square metre nationwide. In rent-controlled cities, prices exceeded €30 per square metre. In cities without controls, they stood closer to €21. The researchers interpret this pattern as evidence that part of the unfurnished rental supply is being deliberately shifted into regulatory gaps to circumvent the rent cap.
GREIX data provides the macro confirmation. While asking rents for standard apartments rose 4.5% year on year in Q4 2025, the share of listings effectively outside robust rent control reached record levels. The rent cap is not preventing higher rents. It is changing the form in which those rents are charged.
Enforcement on paper, avoidance in practice
Defenders of the Mietpreisbremse argue that its impact should not be judged by headline rents alone. Early research by the German Institute for Economic Research found that rent control reduced asking rents by two to four percentage points compared with a counterfactual scenario without controls. That finding still holds. What has changed is the market's response.
Compliance remains weak. In Berlin, asking rents average around 80% above the legally permitted level. Yet enforcement has been minimal: only four fines have been issued, reflecting high legal hurdles and tenant reluctance to confront landlords. Surveys in Munich show that fewer than 3% of tenants invoke the rent cap at all.
From a market perspective, this matters less for the morality of rent setting than for its predictability. Regulation that exists largely on paper creates incentives for avoidance rather than compliance. Furnished and temporary rentals offer a convenient escape route: higher headline rents justified by furniture surcharges, fixed terms that reset pricing more frequently, and a tenant base with limited bargaining power.
The political response is now following the data. The growing prominence of furnished housing has prompted calls for tighter regulation, including clearer definitions, stricter enforcement and potential inclusion of furniture premiums within local comparative rents. Justice Minister Stefanie Hubig has signalled legislative intent, while the rent cap itself has been extended until the end of 2029. Policymakers are preparing to regulate the market segment that expanded most rapidly under the existing regime.
Who benefits, and who bears the risk
For investors, the picture is mixed but clear. In the short term, the evidence points to continued rental growth driven by scarcity, demographic pressure and a broken development pipeline. Existing residential assets in strong locations retain pricing power, particularly where tenant turnover allows resets. The growing reliance on furnished and temporary rentals has supported income growth in segments that would otherwise be capped.
Under the current regime, professional providers of furnished housing have benefited most. Incumbent tenants with long-standing contracts also gain from relative stability. New market entrants – students, trainees, mobile workers and lower-income households – bear the cost.
Looking ahead, regulatory risk is shifting rather than disappearing. The immediate focus is on furnished housing, where tighter definitions, limits on furniture premiums and inclusion in local comparative rents are under discussion. Providers operating in a segment where asking rents have risen by around 80% since 2012 are likely to face increased scrutiny. At the same time, enforcement of the existing rent cap shows little sign of becoming materially more effective.
The GREIX data does not argue for or against rent control. What it shows, with increasing clarity, is how regulation reshapes market behaviour. Rents continue to rise faster than inflation, while supply contracts and pricing power shift into areas of weaker enforcement. For residential investors, the implication is practical rather than ideological: income sustainability and regulatory exposure can no longer be assessed in isolation. They now depend on how deeply an asset is embedded in the regulatory perimeter — and how quickly that perimeter may shift.