Taking In a Subtenant: Getting Permission (2026)

Taking in a subtenant: what does it mean?

Taking in an Untermieter:in (subtenant) means letting a third party use part of your rented flat, or one room — for rent or free of charge. You remain the Hauptmieter:in (main tenant) and therefore stay the landlord's contracting party.

The key point up front: for part of your flat you have an enforceable Anspruch auf Erlaubnis (right to permission) to sublet — you do not depend on the landlord's goodwill.

Your right to permission (§ 553 Abs. 1 BGB)

§ 553 Abs. 1 BGB says: if a berechtigtes Interesse (legitimate interest) in handing over part of the dwelling to a third party arises after you signed the lease, you can demand the landlord's Erlaubnis. This is a genuine right — the landlord must consent unless a wichtiger Grund (serious cause) stands against it.

The decisive distinction is between part and whole: the right under § 553 BGB applies only to part of the flat. The whole flat you may hand over only with the landlord's express consent (§ 540 BGB) — there is no statutory right to that.

Achtung: Always obtain the Erlaubnis in writing before anyone moves in. Subletting without permission breaches the lease — the landlord can issue an Abmahnung (formal warning) and, in serious or repeated cases, terminate, for the whole flat even without notice (§ 540, § 543 BGB). The right under § 553 BGB does not replace the actual permission.

What counts as a berechtigtes Interesse?

The berechtigtes Interesse must have arisen after you signed and must carry some weight. Both economic and personal reasons are accepted, for example:

• the wish to lower your housing costs by taking in a subtenant;
• a partner or a WG-Mitbewohner:in (flatshare housemate) moving in with you;
• a longer work- or study-related stay in another city or abroad while you want to keep the flat;
• changed life circumstances that make company or relief sensible.

Mere convenience is not enough — a concrete financial or life-related reason certainly is. Profit-oriented subletting is not covered: under the BGH judgment of 28 January 2026 (VIII ZR 228/23), generating income that significantly exceeds your own housing costs is no berechtigtes Interesse.

How do I request permission? Step by step

1. Name the Untermieter:in. The landlord may know who is moving in. They need not grant permission "for an unknown person" — give the name and, if asked, the date of birth.
2. State the rooms and the start date. Write which part of the flat (which room) you want to hand over and from when.
3. Set out your berechtigtes Interesse. Explain briefly and concretely why you want to sublet (§ 553 Abs. 1 BGB) — cost-sharing or a stay abroad, for instance.
4. Ask in writing and set a deadline. Make the request by letter, email or in-app message and ask for a reply within a reasonable period (often two to four weeks).
5. Wait for the Erlaubnis and keep it. Let no one move in before permission is granted, and keep both the request and the reply.

For the WG (flatshare) setup and the different liability models, see the guide WG and subletting.

When may the landlord refuse — and when not?

The landlord may refuse the Erlaubnis only for a wichtiger Grund (§ 553 Abs. 1 Satz 2 BGB). Without such a reason, your right prevails.

Situation	Part of the flat	Whole flat
Legal basis	§ 553 BGB	§ 540 BGB
Do you have a right to it?	Yes — Anspruch auf Erlaubnis with a berechtigtes Interesse	No — only with express consent
Landlord may refuse if	wichtiger Grund in the person, overcrowding, or unreasonableness	freely — no duty to consent
Landlord may not refuse if	the only reason is wanting higher rent, or plain reluctance	—
Consequence of unauthorised subletting	Abmahnung, in serious cases Kündigung	Abmahnung, often Kündigung without notice (§ 543 BGB)

If the landlord refuses the Erlaubnis without justification, you can terminate the tenancy extraordinarily with the statutory notice period (§ 540 Abs. 1 Satz 2 BGB) — unless the wichtiger Grund lies precisely in the subtenant's person.

Can the landlord charge an Untermietzuschlag?

Yes, but only if handing over the flat would be unreasonable for them without a reasonable rent increase (§ 553 Abs. 2 BGB). They may then make the Erlaubnis conditional on your agreeing to an Untermietzuschlag (subletting surcharge). In practice roughly 10 to 20 percent of the sublet rent counts as reasonable, to cover the increased wear and tear.

If no extra person moves in through the sublet — for instance a mere change of person after a separation — a surcharge is usually not justified. The burden of proving that the arrangement would be unreasonable without a surcharge lies with the landlord. You need not accept a flat surcharge with no factual basis.

Common mistakes

• Subletting without permission. Even with a right, you must assert it — it does not replace the actual Erlaubnis.
• Handing over the whole flat and citing § 553 BGB. The right applies only to a part; the whole needs consent under § 540 BGB.
• Not naming the Untermieter:in. The landlord need not grant permission "for just anyone".
• Accepting a surcharge unchecked. Verify whether it is justified at all under § 553 Abs. 2 BGB and reasonable in amount.
• Wanting to make a profit. Profit-oriented subletting is no berechtigtes Interesse under the BGH (judgment of 28 January 2026).

HausMaus makes this easier

HausMaus is free for tenants. You send the § 553 BGB request for the Erlaubnis straight from the app to your landlord — with the subtenant's name, the desired start date, the reason, and the choice of whether you are handing over part or the whole of the flat. You can follow the request's status step by step, and the granted Erlaubnis stays neatly filed alongside your other tenancy documents. That way you have the permission to hand whenever it matters later.

See pricing – 1 % of collected rent, free for tenants →