Untermiete and Zwischenmiete: landlord's permission, sublease, Kaution, notice, taxes and Rundfunkbeitrag when you sublet to an Erasmus student in Germany.
In Germany, subletting a room of your home (Untermiete), including for just a few months (Zwischenmiete), is legal and common, on one condition: your landlord's permission. The Civil Code even gives you a right to that permission when you have a legitimate interest in subletting part of the dwelling. After that, you become a landlord yourself: written contract, capped deposit, notice periods, declared income. This guide is for the tenant, or the owner-occupier, who wants to host an Erasmus student in a spare room, in Göttingen or elsewhere in Germany.
First, your landlord's permission
This is the rule that governs everything else. A tenant may not hand over use of the dwelling to a third party without the landlord's consent (§ 540 BGB). But the law immediately tempers that principle: if, after signing your lease, you have a legitimate interest in letting a third party use part of the dwelling, you may demand permission from your landlord (§ 553 BGB). A stay abroad, a change in your finances or a flatmate moving out are classic reasons.
Three practical nuances:
- The landlord may make consent conditional on a reasonable rent increase (Untermietzuschlag) if the sublet is only acceptable to them at that price (§ 553 paragraph 2 BGB).
- The right covers part of the dwelling. Subletting the whole flat while you are away is not covered by it; the landlord's consent is then purely voluntary.
- Ask for permission in writing, naming the person and the duration. Subletting without permission can justify a warning and then a termination.
If you are an owner-occupier, the question does not arise: you are letting a room of your own home, under the flexible regime described in our guide renting your room to an Erasmus student in Göttingen.
The sublease: what it must contain
Once permission is granted, you sign an Untermietvertrag with the student. You become their landlord; your own landlord remains yours, and you remain liable to them for the rent and the state of the flat. The written contract should set out:
| Clause | What to write | Source |
|---|---|---|
| Subject | The room let and the shared areas that may be used (kitchen, bathroom, internet) | common practice |
| Duration | Start and end dates if the stay follows a semester | see below |
| Rent | Amount, what it includes (utilities, electricity, internet), payment date | § 556 BGB |
| Kaution | At most three months' rent excluding utilities, payable in three instalments | § 551 BGB |
| Inventory | The list of furniture and its condition, signed by both parties | common practice |
| Permission | A statement that the main landlord has authorised the sublet | § 540 BGB |
On duration, the regime depends on the room let. If you live in the flat yourself and let a furnished room, you fall under § 549 paragraph 2 no. 2 BGB: notice is short for both sides (by the 15th of a month at the latest, effective at the end of that month, § 573c paragraph 3 BGB) and you do not have to justify a termination. An end date in the contract then mainly serves as a shared reference. If you do not live on site, the general law applies and a fixed term is only valid in the cases of § 575 BGB: see our guide Zeitmietvertrag, Kündigungsverzicht, Kaution.
The paperwork the student will expect from you
Two formalities come up every time, and the student cannot complete them without you.
- The Wohnungsgeberbestätigung. The subtenant must register their address within two weeks of arriving (§ 17 BMG), and it is the person providing the housing, so you, who confirms the move-in (§ 19 BMG). The confirmation states your name and address, the owner's name if you are not the owner, the address of the dwelling, the move-in date and the name of the person moving in. Failing to hand it over carries a fine of up to €1,000 (§ 54 BMG). From the student's side, we explain why this piece of paper matters so much in Wohnungsgeberbestätigung: why your landlord has to give it to you.
- The Rundfunkbeitrag. The broadcasting fee is paid once per dwelling. A sublet room that can only be reached by walking through your flat is part of your dwelling: the subtenant has no separate fee to pay, the flat's fee is what counts (rundfunkbeitrag.de, information for students). Say so clearly to the student, who often receives a letter from the Beitragsservice after their Anmeldung. More in Rundfunkbeitrag: who pays in a shared flat.
Taxes: the €520 rule and beyond
The rent you collect is in principle taxable rental income (§ 21 EStG), to be declared in Anlage V of your tax return. The tax administration does, however, provide a simplification rule: when you temporarily let part of the home you occupy yourself, or temporarily sublet part of the home you rent, and the receipts do not exceed €520 in the year, the tax office may refrain from taxing that income (R 21.2 paragraph 1 of the income-tax application guidelines, official income-tax handbook of the Federal Ministry of Finance).
Two things to remember:
- It is a threshold, not an allowance: one euro above and all receipts become taxable. A semester of subletting exceeds that threshold in almost every case.
- Above it, you declare the receipts and deduct the share of costs attributable to the room let (the rent you pay yourself pro rata to floor area, electricity, internet, furniture). The taxable result is often small. For a student staying one semester the calculation stays simple; when in doubt, a Steuerberater or a tax-help association (Lohnsteuerhilfeverein) will confirm your situation.
Finding the right student and avoiding the traps
A room in Zwischenmiete for a semester is exactly what Erasmus students arriving in Göttingen look for: they quickly find that the Studentenwerk halls run on waiting lists and turn to WGs, as we describe in finding a WG in Göttingen. So you are in a position to choose.
A few habits that protect both sides:
- A viewing or a video call before any commitment, never a transfer "to reserve" before signing. Fake profiles exist on both sides: our anti-scam advice lists the warning signs.
- A written contract and an inventory, even for three months. That is what settles the return of the Kaution without a dispute.
- A flat-rate Warmmiete (utilities, electricity and internet included) for a short stay: the student knows what they pay, and you have no statement to send after they leave.
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FAQ — Subletting to a student in Germany
Do I need my landlord's consent to sublet a room? Yes, always (§ 540 BGB). But if you have a legitimate interest that arose after signing your lease, you may demand permission to sublet part of the dwelling; the landlord may only ask for a reasonable rent increase (§ 553 BGB).
What Kaution can I ask my subtenant for? At most three months' rent excluding utilities, payable in three instalments (§ 551 BGB). An inventory signed at move-in avoids disputes when it is returned.
Does the subtenant have to pay the Rundfunkbeitrag? Not separately if their room can only be reached through your flat: the fee is paid once per dwelling (rundfunkbeitrag.de). If the room has its own entrance from the stairwell or outside, it counts as a separate dwelling.
Do I have to declare the rent from a sublet of a few months? Yes, it is rental income (§ 21 EStG). A simplification rule allows a temporary sublet of part of the dwelling with receipts of no more than €520 in the year to go untaxed; above that, you declare everything and deduct the room's share of costs.
What notice applies to a furnished room in my flat? If you live in the flat and let a furnished room, either party may give notice by the 15th of a month at the latest, effective at the end of that month (§ 573c paragraph 3 BGB), without having to give a reason (§ 549 paragraph 2 BGB).
This article is for information and does not replace official sources or legal or tax advice. Studroof is a passive listings platform, not an estate agency or a property manager. Subletting and tax rules change: always check your situation on gesetze-im-internet.de and with the Federal Ministry of Finance. Last updated: September 2026.