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Reference rent · Rent cap · Consent
Rent Increase under § 558 BGB: How to Make it Effective
- All deadlines from the cooling-off period to the action for approval
- The four admissible grounds for appeal – and which one works without a rent index
- How the capping limit is calculated correctly
- Why an increase is worthwhile even if you want to sell
- 15For how many months must the rent remain unchanged
- 20 %Cap limit within three years
- 2Tenant's reflection period of months
- 3Comparable properties are sufficient as justification
Prerequisites
The deadlines on which everything depends
A rent increase in accordance with Section 558 of the German Civil Code (BGB) is not a unilateral right, but a claim for consent. Therefore, it is subject to deadlines – and therefore it fails if one of them is not adhered to.
| Dot | Rule | Basis |
|---|---|---|
| Rent unchanged since | 15 months from the date of becoming effective | § 558(1) Sentence 1 of the German Civil Code |
| Earliest point of desire | 12 months after the last increase | Section 558, Paragraph 1, Sentence 2 of the German Civil Code |
| Form of request for increase | Textform – E-mail sufficient, no signature required | Section 558a (1) of the German Civil Code |
| Tenant's reflection period | by the end of the second calendar month after receipt | Section 558b(2) of the German Civil Code |
| Coming into effect of the increase | at the beginning of the third calendar month after receipt | Section 558b Paragraph 1 of the German Civil Code (BGB) |
| Prompt for the action for consent | 3 more months after the cooling-off period expires | § 558b para. 2 sentence 2 of the BGB |
| Contribution ceiling | 20 % over 3 years; in areas with a tight housing market, 15 % | Section 558, Paragraph 3 of the German Civil Code (BGB) |
To work backwards: if the higher rent is to take effect from 1 July, the request must be received no later than March, and the rent must not have been changed since April of the previous year. Increases due to modernisation under § 559 BGB and adjustments to operating costs do not count as a rent increase within the meaning of the lock-out period.
The request is directed at all tenants listed in the contract and originates from all landlords. In the case of an inheritance community or a company, representation must be identifiable – a request for an increase „on behalf of“ without proof of authorisation can be rejected according to § 174 of the German Civil Code (BGB).
Reasoning
Four ways to provide evidence of the local comparative rent
The law names them definitively. Which route is practicable depends almost exclusively on whether your city has a rent index.
Rent index
The simplest way, where it exists. Municipalities with more than 50,000 inhabitants have been obliged to create them since the Rent Index Reform Act. A qualified rent index according to § 558d BGB has additional presumptive effect – and must be attached to or named in the request even if you provide other reasons (§ 558a (3) BGB).
Three comparable flats
The most practical way in cities without rent indexes. According to § 558a (2) no. 4 BGB, the designation of three comparable flats in terms of type, size, fittings, condition, and location, including energy efficiency, is sufficient. Flats from one's own portfolio are permissible – this is a significant advantage for owners of multiple properties.
Expert report
Durable, but expensive. An expert report from a publicly appointed and sworn expert regularly costs a four-figure sum and is therefore usually only worthwhile if several units in the same building are raised simultaneously.
Rental database
Theoretically provided for, practically rare. Outside of some major cities, there are hardly any databases in the sense of § 558e BGB. In Saxony-Anhalt and Thuringia, this route plays virtually no role.
The justification must enable the tenant to conduct their own examination. In the case of comparable flats, this means the street, house number, floor, and position on the floor must be precise enough to identify the flat, as well as the size, features, and the net cold rent paid there. A general reference to „local customary rents“ is insufficient and renders the demand invalid.
Order
From preparation to higher rent
The effort is almost entirely in the first three weeks. After that, the process runs itself – provided the documents are correct.
- 1Week 1
Inventory per unit
Current net cold rent, living space, date of last rent increase, features. Create a table for all units – in practice, some older contracts are well below market level, while others are already above it.
- 2Weeks 1–2
Provide evidence of comparable rent
Check the rent index. If one is missing, compile three comparable flats with their address, size, amenities, and net cold rent paid. Flats from one's own portfolio are permissible and often the only reliable source in smaller towns.
- 3Weeks 2–3
Check contribution ceiling
The starting point is the net cold rent from three years ago, not the current rent. Modernisation increases according to § 559 BGB are disregarded when calculating the cap. Furthermore, check whether a state ordinance for your municipality reduces the cap to fifteen percent.
- 4Week 3
Draft and serve a demand
A text form is sufficient, but proof of access is still useful. The following must be included: previous and new net cold rent, amount of increase, date of effect, justification, and a request for agreement with a deadline.
- 5Month 1-2
Cooling-off period
The tenant has until the end of the second calendar month after receipt. If they do not respond, this is considered a rejection – silence does not imply consent. Partial consent is possible and common in practice.
- 6Month 3
Effectiveness or lawsuit
If the tenant agrees, they will owe the higher rent from the beginning of the third calendar month after receipt. If they do not agree, you will have a further three months to file a legal claim for consent – this deadline is an exclusion period.
- 7Month 4–5
Action for declaration of consent
The local district court has jurisdiction. The amount in dispute is the annual amount of the increase (§ 41 para. 5 GKG), which makes the proceedings comparatively inexpensive. The judgment replaces the consent retroactively to the original date.
From the first line to the higher rent in the account, around four months pass if there is agreement, and about nine to twelve months if legal action is taken. However, the return is permanent – which is why the effort almost always pays off, even with small amounts.
Contribution ceiling
How to calculate correctly
The rent cap is the second limit alongside the locally comparable rent. Both apply concurrently – the lower of the two is always decisive.
The starting point is the net cold rent that was owed three years before the new rent came into effect. If this was €400, the upper limit is €480 – even if the local comparative rent is €520. However, if the comparative rent is €450, the limit is €450.
Increases under § 559 BGB due to modernisation are not taken into account in this calculation; they run alongside § 558 BGB and have their own cap. Operating cost adjustments also do not count, as they do not affect the net cold rent.
| Autumn | Invoice | Result |
|---|---|---|
| Rent 3 years ago €400, comparable rent €520 | 400 € + 20 % = 480 € | Increase to €480 possible |
| Rent 3 years ago €400, comparable rent €450 | The comparable rent is lower | Increase to €450 possible |
| Municipality with a reduced limit, rent €400 | 400 € + 15 % = 460 € | Increase to a maximum of €460 |
| Modernisation additionally | 8 % of costs per annum, own cap | is covered by § 558 BGB |
The reduced cap of fifteen percent only applies where a state ordinance designates the area as a tense housing market. This is not the case in large parts of Saxony-Anhalt and Thuringia – check it anyway, as the ordinances are regularly reissued.
Typical mistakes
Six reasons why increases are ineffective
All six are formal in nature. All six will take at least fifteen months because the requirement needs to be completely re-established.
- Blackout period not observed. The rent must have been unchanged for fifteen months at the time it becomes effective, and the request may be made no earlier than twelve months after the last increase. Those who write too soon will not receive approval and will have to start over.
- Justification is too general. The tenant must be able to verify the increase themselves. Comparable flats must include their address, floor, size, amenities, and the net rent paid there. Without this information, the demand is invalid.
- Gross rent instead of net cold rent applied. § 558 BGB refers exclusively to the net cold rent. Anyone who includes advance payments for operating costs regularly exceeds the cap without realising it.
- Not all tenants have been contacted. The request must be addressed to all contracting parties and emanate from all landlords. If one is missing, it is entirely invalid – even towards those who received it.
- Qualified rent index not provided. If a qualified rent index exists for the municipality, you must also disclose its details if you provide justification with comparable flats or expert reports (§ 558a(3) of the German Civil Code).
- Let the deadline for appeal expire. Once the reflection period has expired, there are exactly three months remaining for the legal challenge. This period is a forfeiture period – after that, only a completely new request will help.
Classification
What the increase means for the value of your home
The real effect of a rent increase is not in the monthly rent. It lies in the multiplier.
Flats are valued based on the annual net cold rent and a factor. Whoever increases the rent of a unit by 60 euros a month increases the annual rent by 720 euros – and with a factor of 13, increases the calculated value of the property by around 9,400 euros. With six units and the same increase, that's over 56,000 euros. This is why a thoroughly implemented rent adjustment before a sale is almost always the most rewarding measure – significantly more rewarding than any cosmetic renovation.
The catch is the time. Between the initial writing and the first higher payment, it takes around four months with agreement, and up to a year with an objection. And the value only fully kicks in when the higher rent is actually flowing and can be proven – a merely announced increase won't be paid by a buyer.
We are writing this from the buyer's perspective. The Rosenbaum Group buys apartment blocks for its own portfolio, and we are constantly coming across properties where the rents haven’t been adjusted for ten years. For us, this isn’t a shortcoming but an opportunity – we factor it in and raise the rents ourselves after purchase. To be honest, that’s precisely part of our return on investment.
This leads to a simple decision for you. If you want to keep the house, go through with the rent increase – the steps for this are outlined above, and the additional income will be yours permanently. If you intend to sell anyway and are only pursuing the increase for that purpose, do the honest calculation: you are investing twelve months of effort and conflict with the tenants for an increase in value that a buyer, who already sees the potential, will partially pay for anyway. In that case, it is better to ask beforehand what your house is worth in its current condition.
Frequently Asked Questions
Rent increases under § 558 BGB – the most common questions
How often am I allowed to increase the rent?
A request for an increase is possible no earlier than twelve months after the last increase, and the rent must have remained unchanged for fifteen months at the time the increase takes effect. Within three years, the net cold rent may not increase by more than twenty percent.
Is an email enough?
Yes. Section 558a (1) of the German Civil Code (BGB) only requires written form. A handwritten signature is not necessary. Nevertheless, ensure proof of receipt – in the event of a dispute, you must be able to prove it.
What applies if there is no rent index?
Then justify with three comparable apartments according to § 558a paragraph 2 number 4 BGB or with an expert report. Apartments from your own portfolio may be named – the address, floor, size, furnishings, and the net cold rent paid there are required.
What happens if the tenant does not respond?
Silence is considered a refusal. After the reflection period has expired, you have three months to sue for consent. If you miss this deadline, you will have to restart the entire procedure.
Can the tenant terminate if I increase [the rent]?
Yes, he has a special right of termination until the end of the second month after receipt, with effect at the end of the month after next (§ 561 BGB). The increase will then not take effect. In situations with high demand, this is rarely a problem; in regions with vacancies, it is better to factor it in.
Is the increase still worth it if I want to sell?
Mathematically, yes – every permanently higher annual rent increases the value by a multiple of the factor. Practically, it depends on the timing: the effect only comes into play when the higher rent is actually received. Those who want to sell within the next six months will usually not be able to achieve this.
Alternative
Sell potential instead of unlocking potential
We buy apartment buildings with old rental agreements below market value and increase the rents ourselves after purchase. This is part of our calculation – and it means we are also valuing the potential.
What suits your situation?
What do you do?
Non-binding, no commission, and no agency agreement. We are long-term holders – you speak directly with the buyer.
Sources and status of the data
- §§ 174, 557a, 557b, 558, 558a, 558b, 558c, 558d, 558e, 559, 561 BGB – gesetze-im-internet.de
- § 41(5) GKG for the amount in dispute for a consent action – gesetze-im-internet.de
- Rent Index Reform Act and Rent Index Ordinance on the obligation to create rent indices
All details checked on 03.08.2026. Example calculations are for illustrative purposes only. This contribution does not replace legal advice in individual cases.
Further
Relevant posts and pages
- Rent Index Weißenfels – how to prove the customary comparable rent without a rent index.
- Tenant not paying – what to do – what applies if the increase fails due to payment behaviour.
- Rosenbaum Group Real Estate Acquisition – Direct sale to a property owner who also assesses rental potential.
Have rents not been adjusted for years?
We don't just assess the current rent, but also what is realistically achievable – and we openly explain how we calculate it.