Flat Swap in Berlin: When Trading Flats Keeps Your Rent
The baby is due in spring, the flat has two rooms, and the asking rent for three rooms in your Kiez starts at a number that makes you close the app. Meanwhile, two floors up, a retired couple rattles around in a 90 m² flat they would happily trade for something smaller. In Berlin that trade has a name, Wohnungstausch, and for some tenants it is the cheapest move in the city.
For others it is a trap. Whether a flat swap in Berlin keeps your rent depends almost entirely on who owns the two flats. With the seven state-owned housing companies, both net cold rents stay exactly as they are. With a private landlord, a swap is a new lease, and the rent can jump. The gap between those two outcomes is easily a few thousand euros a year.
The "Schlange" on Schlangenbader Straße in Wilmersdorf, built over the motorway and run by degewo, one of the seven state-owned companies on the swap portal.
Who owns your flat decides everything
Before you look at a single swap ad, find out who your landlord is. It is printed on your lease and on every rent letter. Berlin has about 370,000 flats owned by the city through seven companies: degewo, GESOBAU, Gewobag, HOWOGE, STADT UND LAND, WBM and berlinovo. Everything else, from a big listed company to the man who owns your Altbau in Neukölln, counts as private for this question. Housing co-ops (Genossenschaften) follow their own internal rules.
That one fact sorts you into one of three situations:
Both flats are state-owned: you can use the official swap portal, and both rents stay the same.
Your flat is state-owned and you want to shrink: the downsizing offer can find you a smaller flat without a swap partner.
Either flat is private: a swap needs both landlords to agree, and the incoming tenant signs a new lease at a rent the landlord sets within the law.
The state-owned swap portal: both rents stay put
Since September 2018 the state-owned companies have run a shared swap portal on inberlinwohnen.de. Any main tenant of one of the seven companies can offer their flat there and search the offers of tenants at all seven, so a degewo tenant in Wilmersdorf can swap with a HOWOGE tenant in Lichtenberg. The rule that makes it special is printed right on the portal: the net cold rents of both flats stay unchanged. You move into the other flat at the other tenant's rent, and they move into yours at yours.
The conditions are short:
You are the main tenant (Hauptmieter) of a flat with one of the seven companies.
Your lease has not already been terminated.
Your company has an email address on file for you, which the portal uses to verify you.
Each company checks the swap request before anything is signed, and both moves have to happen at the same time. You and your swap partner organise the moves yourselves. If the flat you want is a social housing flat, expect to need a matching WBS certificate, because the company still has to let that flat by the rules.
The catch is how rarely it works. In 2024 the swap route produced 327 new leases, 309 of them started on the portal, across a stock of roughly 370,000 flats. A swap needs two households who want each other's flat at the same moment, in the right district, on the right floor. I would treat the portal as a slow background search that you check every week or two, and keep it running for months.
Prefab towers in Marzahn. The big estates in the east and the outer west hold much of the state-owned stock, so that is where most swap offers sit.
The downsizing offer: no swap partner needed
If your flat has grown too big, there is a quieter route that skips the matching problem. Since 1 September 2025 the state-owned companies run a Wohnungswechsel programme for main tenants who want to move into a flat that is at least one room and at least 10 m² smaller. Your own company then makes you up to three offers within twelve months, from its own stock only, not across the seven companies.
The rent rule is the part to read twice. The smaller flat is let at the local comparative rent (ortsübliche Vergleichsmiete) without a new-letting surcharge, and the move is timed so you do not pay two rents. That is not the same promise as the swap portal. If you have lived in your flat for twenty years and pay well under the Mietspiegel, a smaller flat at the Mietspiegel rent can cost almost as much as your bigger one. The Berliner Mietspiegel 2026, valid since 28 May 2026, puts the median at EUR 7.71 per m².
In 2024, before the new programme, these internal moves already produced 716 new leases, more than twice the swap route. My advice: if you only want to shrink, write to your company about the Wohnungswechsel first and use the portal on the side.
The housing ring around Mehringplatz in Kreuzberg. A swap only happens when two households in places like this want each other's flat in the same month.
A private swap is really a new lease
Scroll through the big rental portals and you will find a striking share of swap ads: in a survey on 12 May 2025, 2,488 of 5,738 Berlin rental ads on ImmoScout24, 43 percent, were swap offers. Most of them involve private landlords, and that changes the deal completely.
German tenancy law gives you no right to swap. The Berliner Mieterverein argued for one in a Bundestag hearing in 2023; until a law changes that, both landlords have to agree. In practice each tenant ends their lease and the other one signs a new one, and the landlord sets the new rent. The limit is the Mietpreisbremse, extended in Berlin until 31 December 2029: at re-letting the rent may not exceed the local comparative rent by more than 10 percent. Three exceptions matter for a swap:
The previous rent: if the outgoing tenant already paid more than the cap allows, the landlord may keep that rent.
New builds and big refurbishments: a flat first let after 1 October 2014, or first let after a comprehensive modernisation, is outside the cap.
Temporary lets (zum vorübergehenden Gebrauch) are outside the cap, and the Mieterverein reports that furnished short lets have grown sharply since it came in, so read the lease type before you sign.
An Altbau corner on Oranienplatz. In a privately owned building like this a swap only happens if the landlord signs a new lease with the incoming tenant.
My advice for a private swap: ask both landlords in writing what the new lease would cost before anyone gives notice. If one of them will not say, the swap is not real yet. And a swap partner who asks for money for "their" flat is selling something that is not theirs to sell.
What the next flat costs by each route
The board below takes your flat and the one you want and prices the same flat four ways: on the state-owned portal, through the downsizing offer, as a private swap or new lease, and as a fresh search at the median asking rent.
The comparison that matters is the bottom bar. According to the IBB Housing Market Report 2025, the median asking rent in Berlin listings was EUR 15.78 per m² in 2025, EUR 19.22 in the inner city and EUR 13.01 in the outer districts, more than twice the local comparative rent. The members of the BBU, mostly the state-owned companies and the co-ops, charged an average of EUR 7.10 per m² in existing leases. On a 70 m² flat the gap between those two figures is about EUR 7,300 a year. That is why a swap, when it works, is the best deal on the Berlin housing market.
My plan for a flat swap in Berlin
Start with the lease: who is the landlord, and what is the net cold rent per m². If you are with one of the seven state-owned companies, register on the portal today and write your wish list wide, more districts and more floors than feel comfortable, because a narrow search almost never matches. If you want to shrink, send the Wohnungswechsel request to your own company at the same time. If your flat is private, treat every swap ad as a new lease with a friendly tenant attached, and get both rents in writing first.
Prefab blocks and a green courtyard on Rosenbecker Straße in Marzahn. A wish list wide enough to include estates like this gives a swap far more chances to match.
Then plan the day itself. Both moves happen on one date, so book the van early and, if your street is tight, a no-parking zone for the moving van. Before you give notice anywhere, read my notes on the notice period for a Berlin flat and on getting your deposit back. If the new landlord quotes a rent that looks too high, the Mieterverein can check it against the cap, and my post on rent increases in Berlin explains what can change after you move in. When the companies change the swap rules or the next Mietspiegel lands, my weekly newsletter is where I will say so.
Image credits
Source and licence details for the 2 photographs used in this article.
The housing ring around Mehringplatz in Kreuzberg: Gunnar Klack, CC BY-SA 4.0, via Wikimedia Commons.
An Altbau corner on Oranienplatz in Kreuzberg: Gunnar Klack, CC BY-SA 4.0, via Wikimedia Commons.