Check your Mietvertrag before signing (2026)

Why you should check the Mietvertrag before signing

A Mietvertrag (lease) is signed quickly — and then often runs for years. Many contracts contain standard clauses that the Bundesgerichtshof (BGH, Germany's Federal Court of Justice) struck down long ago, yet they still appear in pre-printed forms. The good news: a void clause does not bind you, even if you signed. It is invalid from the outset (§ 307 BGB), and the statutory rule takes its place — which is almost always better for tenants.

Checking before you sign still pays off. You know what you are agreeing to, you can ask for corrections, and you avoid disputes later. The most important points come first below; the rarer ones follow.

How high may the Kaution be? (§ 551 BGB)

The Kaution (security deposit) may be at most three Nettokaltmieten (net cold rents, § 551 Abs. 1 BGB). What counts is the rent alone, without Nebenkosten (service charges) and without heating — not the warm rent. For a Staffelmiete (stepped rent) or Indexmiete (index-linked rent), the starting rent applies.

You also have the right to pay the Kaution in three equal monthly instalments (§ 551 Abs. 2 BGB). The first is due at move-in, the other two in the following months. A clause demanding more than three Nettokaltmieten, or excluding instalments, is void — and you can reclaim anything overpaid.

Is the Schönheitsreparaturen clause valid? (§ 307 BGB)

By law, redecorating is the landlord's job (§ 538 BGB). You are only obliged if a valid Schönheitsreparaturen (decorative repairs) clause transfers the duty to you. The BGH has declared many such clauses void:

• Rigid fixed deadlines ("kitchen every 3 years, fixed") are void, because they would apply even to freshly painted rooms.
• Quotenabgeltung clauses (a pro-rata payout for redecoration not yet due) are void (BGH, 18.03.2015, VIII ZR 242/13).
• If the flat was handed over unrenovated without adequate compensation, the clause is also void (BGH, 18.03.2015, VIII ZR 185/14).

If the clause is void, the whole duty falls back to the landlord — you redecorate nothing on moving out. More in the guide on Schönheitsreparaturen.

Is the Kleinreparaturen clause permissible? (§ 535 BGB)

In principle the landlord bears maintenance (§ 535 Abs. 1 BGB). A Kleinreparaturen (minor repairs) clause can shift small repair costs to you — but only if it is narrowly limited. It is valid only if all three conditions are met:

1. a per-repair cap (case law usually sets this at roughly 100 to 120 euros),
2. an annual cap (typically around 6 to 8% of the annual Nettokaltmiete), and
3. a limit to items you use frequently (e.g. taps, light switches, window handles).

If one of these limits is missing or set too high, the entire clause is void — and the landlord pays for all repairs. Important: the clause may never oblige you to arrange the repair yourself or to bear the full cost of a more expensive repair.

Is your rent above the Mietpreisbremse? (§ 556d BGB)

In areas with a strained housing market, the rent at the start of a tenancy may exceed the ortsübliche Vergleichsmiete (locally customary comparative rent) by at most 10% (the Mietpreisbremse, rent cap, § 556d BGB). Before signing, check whether your city is covered and what the comparative rent for your flat is. If the agreed rent is higher, the excess is void, and you can reclaim it with a qualifizierte Rüge (qualified challenge, § 556g BGB). The Mietpreisbremse runs nationwide until 31 December 2029. More in the guide on the Mietpreisbremse.

Important: A void clause is invalid — but the rest of the Mietvertrag stays valid and binds you. A clause also does not become valid just because you signed it. So do not let yourself be pressured: check the rent against the Mietpreisbremse before signing, and sign nothing you do not understand.

Void vs. valid clauses — the quick comparison

Clause in the Mietvertrag	As a rule
Kaution above 3 Nettokaltmieten	void (§ 551 BGB)
Kaution must be paid all at once	void (§ 551 Abs. 2 BGB)
Schönheitsreparaturen with rigid deadlines	void (§ 307 BGB, BGH)
Quotenabgeltung clause	void (BGH 18.03.2015)
Kleinreparaturen clause with no per-repair/annual cap	void
Blanket ban on pets (dog/cat)	void (BGH VIII ZR 168/12)
Kündigungsverzicht longer than 4 years	void (BGH)
Rent > 10% over comparative rent (capped area)	void (§ 556d BGB)
Kaution up to 3 Nettokaltmieten, in 3 instalments	valid
Schönheitsreparaturen with flexible deadlines	usually valid
Kündigungsverzicht up to 4 years	valid

What must a valid Mietvertrag contain?

A valid Mietvertrag needs no particular form (even an oral contract would be valid). Written form is customary and sensible, though — and a lease for more than one year must be in writing, or it counts as open-ended (§ 550 BGB). Look for these details:

• the parties (every tenant by name) and the exact flat
• the Nettokaltmiete and the Nebenkosten advance payment, shown separately
• the start date and any fixed term, plus notice periods
• the amount of the Kaution (max. 3 Nettokaltmieten)
• for a Staffelmiete (§ 557a BGB): each step with amount and date; for an Indexmiete (§ 557b BGB): the link to the consumer price index

Common tenant mistakes

• Signing blind. Standard forms often contain clauses struck down long ago.
• Paying more than three Nettokaltmieten in Kaution, or waiving the right to instalments.
• Signing under pressure without checking the rent against the Mietpreisbremse.
• Following a void clause — for instance redecorating voluntarily — when there is no duty.
• Leaving oral promises out of the contract; only what is written down counts.

With HausMaus it's simpler

HausMaus is free for tenants. You upload your Mietvertrag and the app reads it: it shows the Kaltmiete, Warmmiete, Kaution and Kündigungsfrist at a glance and flags risky clauses on Schönheitsreparaturen, Kleinreparaturen and Schriftform. On top of that, the Mietpreisbremse check compares your rent against the ortsübliche Vergleichsmiete (§ 556d BGB). So you can see what to watch for before you ever sign.

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