WG: splitting rent and Nebenkosten fairly (2026)
Updated 6/17/2026 · HausMaus Redaktion
How you split rent and Nebenkosten (operating costs) in a WG (flatshare) depends on the lease: if everyone is on one contract, all are Gesamtschuldner (joint and several debtors) — each can be charged the full rent (§ 421 BGB). Internally, an equal share applies in case of doubt (§ 426 BGB), but you may agree any fair split: per head, by room size, or by consumption. A written WG agreement prevents disputes.
What matters when splitting in a WG
In a WG (Wohngemeinschaft / flatshare) several people share one flat — and so share the rent and the Nebenkosten (operating costs). How this works legally turns above all on one question: how is the lease set up? That determines who is liable to the landlord and how you split fairly among yourselves.
The most important fact first: if everyone is on the lease together, you are liable as Gesamtschuldner (joint and several debtors, § 421 BGB). That means the landlord may demand the full rent from any single one of you, not just your room's share. How you split among yourselves is a separate matter.
Two WG models — two liability situations
| Joint main lease | Main tenant + subtenants | |
|---|---|---|
| Who is a tenant? | everyone, equally | only the main tenant |
| Liability to landlord | all jointly & severally (§ 421 BGB) | only the main tenant |
| Default risk | borne by everyone together | borne by the main tenant |
| Subletting | – | permission needed (§ 553 BGB) |
With a joint main lease everyone is directly protected and equally entitled — but also carries the shared risk if one person doesn't pay. With subletting, only the main tenant is the landlord's contract partner; that person must obtain permission to sublet (§ 553 BGB) and stands behind their subtenants.
External vs. internal relationship (§ 421 / § 426 BGB)
Separating these two levels saves a lot of trouble:
- External (towards the landlord): with a joint lease everyone is liable for everything (§ 421 BGB). The landlord chooses whom to charge.
- Internal (among yourselves): here your agreement governs. Without a different arrangement, an equal share applies in case of doubt (§ 426 Abs. 1 BGB). If a flatmate doesn't pay and you step in, you can reclaim the money from them.
Achtung: If you cover a defaulting flatmate, you are not paying "out of kindness" — you are discharging a shared debt. Document who paid what; that is the basis for your settlement claim under § 426 BGB.
Fair distribution keys: per head, by m², by consumption
How you split internally is up to you — as long as everyone agrees and it is in writing. Three proven keys:
| Key | How it works | Good for |
|---|---|---|
| Per head | everyone pays the same | equal-sized rooms, shared costs |
| By room size (m²) | share = your m² ÷ total m² | rooms of different sizes (base rent) |
| By consumption | by measured values | electricity, hot water, where measurable |
Often a mix is fairest: base rent by room size, general Nebenkosten per head, consumption-based items by consumption.
Step by step: organising the WG kitty
- Clarify the lease. Joint main lease or subletting? Liability follows from that.
- Set the distribution key. Per head, by m², or a mix — decide together.
- Write a WG agreement. Who pays what share, by when, into which account. Include the deposit and move-out rules too.
- Check the Nebenkostenabrechnung together. It arrives for the tenant party — review it within the 12-month deadline (§ 556 Abs. 3 BGB) and split the result (refund or Nachzahlung) by your key.
- Handle tenant swaps cleanly. When a flatmate leaves, agree a contract amendment with the landlord and a clear internal settlement (deposit, open Nebenkosten).
Common mistakes
- Verbal arrangements — no proof in a dispute or at move-out.
- Assuming "only my room" — under a joint lease you are liable for the whole rent (§ 421 BGB), not just your share.
- Subletting without permission — without consent under § 553 BGB you risk trouble, up to termination.
- Splitting Nebenkosten unchecked — errors in the statement pass unchecked to every room.
HausMaus makes it easier
HausMaus is free for tenants and helps WGs split rent and Nebenkosten transparently: you store your distribution key, see who has paid which share, and keep open amounts in view. When the Nebenkostenabrechnung arrives, the app helps you check it against § 2 BetrKV and keep to the 12-month deadline under § 556 BGB — before you share out a refund or Nachzahlung within the WG. Wohnen, geregelt.
Frequently asked questions
In a WG, is everyone liable for the full rent?
If everyone is an equal tenant on the same lease, yes: you are liable as Gesamtschuldner (joint and several debtors, § 421 BGB). The landlord can demand the entire rent from any single one of you — but only once in total. If a flatmate doesn't pay their share, the landlord can turn to the others, who can then reclaim the amount internally (§ 426 BGB).
How do we split rent and Nebenkosten internally?
Freely, as long as everyone agrees. In case of doubt — i.e. with no other arrangement — an equal share applies to all under § 426 Abs. 1 BGB. Three keys are common and fair: per head (everyone equal), by room size (more m² means a bigger share), or by consumption (e.g. for electricity or hot water where it can be measured). Put the chosen split in writing.
What is the difference between a joint lease and subletting in a WG?
With a joint main lease (Hauptmietvertrag) everyone is a direct tenant and liable jointly and severally (§ 421 BGB). In a Hauptmieter–Untermieter WG only one person is the main tenant, who sublets rooms to the others (with permission under § 553 BGB). Then only the main tenant is liable to the landlord and carries the default risk if a subtenant fails to pay.
Who receives the Nebenkostenabrechnung in a WG?
The landlord issues one Nebenkostenabrechnung to the tenant party — the tenants named in the lease, or the main tenant. The WG handles the internal split between rooms itself, using the agreed key. The 12-month deadlines under § 556 Abs. 3 BGB apply to the tenant party, so check the statement together and in good time.
A flatmate moves out — who is liable then?
As long as a flatmate is on the main lease, they remain liable — even after moving out — until released from the contract or the lease ends. A clean tenant swap (releasing the leaver and adding the successor via a contract amendment with the landlord) creates clarity. Settle the deposit and any open Nebenkosten internally at the same time.
Sources
This guide is based on the statute text and official sources. You can read the cited paragraphs in the original here: