1. Case Where the Increase Rate is Undetermined or Vague in the Contract

If there is no increase rate in the Rental Agreement, is an increase applied? Can the Landlord request an increase? In the decisions of the Court of Cassation and the Regional Court of Justice, if the increase rate is not explicitly stated in the lease agreement or is indicated with vague expressions such as “at the inflation rate”, “at the legal rate”, this condition is considered not “definite and specific”.

Invalidity of the Increase Condition: If the increase rate is not specified in the contract or if it is not clear which rate (TEFE, TÜFE, ÜFE) will be applied, the increase condition is invalid. According to the decisions of the 3rd Civil Chamber of the Court of Cassation (E. 2020/237) and the 6th Civil Chamber of the Court of Cassation (E. 2012/16728k), since the increase condition is not definite and specific, the landlord’s unilateral determination cannot be relied upon.

Principle of Fixed Rent: The 3rd Civil Chamber of the Gaziantep Regional Court of Justice (E. 2017/708) stated that if no increase condition is stipulated within the 5-year contract period, it is legally not possible to apply an increase to the rent and that the tenant has the right to keep the rent fixed. Similarly, the 3rd Civil Chamber of the Court of Cassation (E. 2017/5904) emphasized that in contracts without an increase clause, the rent should remain fixed at the initial amount.

2. The Effect of the Tenant Voluntarily Making an Increase in the Past

The precedent decisions regarding the situation that forms the basis of the problem, namely “the tenant paying with an increase for 2 years and not paying in the 3rd year”, support the legality of this tenant’s stance.

Binding Nature of Past Payments: 

In the decision numbered 2020/237 of the 3rd Civil Chamber of the Court of Cassation, the specific case where the tenant made payments with an increase in good faith after the start of the contract, but did not maintain this increase in subsequent periods, was examined. The decision stated that the tenant’s payment with an increase in previous periods would not validate an indefinite increase condition, and the landlord failed to fulfill their burden of proof.

Non-occurrence of Default: 

The fact that the tenant made payments at the CPI rate in the past does not make an unwritten contractual obligation permanent. The 6th Civil Chamber of the Court of Cassation (File No. 2011/10959) ruled that the tenant’s payment with an increase at the CPI rate would not constitute an obligation exceeding the original rent amount due to the invalid increase clause in the contract. Therefore, if the tenant does not apply an increase in the 3rd year, they are not considered to be in default due to the unpaid increase difference and cannot be evicted.

3. Tenant’s Right Not to Apply an Increase in the 3rd Year

In light of the examined decisions, if there is no explicit provision in the contract, the tenant has the right not to apply an increase in the 3rd year.

Rejection of Unilateral Rent Increase Request: The 6th Civil Chamber of the Court of Cassation (E. 2015/8838) stated that it is unlawful for the plaintiff (landlord) to demand an increased rent amount in contracts where no rent increase clause was agreed upon. The tenant can continue to pay based on the amount specified in the contract or the last accepted and paid amount.

Legal Consequence: The 6th Civil Chamber of the Court of Cassation (E. 2015/12224K) found it erroneous for the court to rule that default occurred by increasing the rent at the PPI rate, even though no increase clause was stipulated in the contract. It was deemed sufficient for the tenant to pay the amount written in the contract.

4. Landlord’s Rights and Rent Determination Lawsuit

While the tenant has the right not to agree to an increase, this does not mean that the rent amount will remain fixed indefinitely. However, this increase is not automatic; it must be determined by a court decision.

Necessity of a Rent Determination Lawsuit: The 3rd Civil Chamber of the Court of Cassation (E. 2018/2245) stated that even if there is no increase clause in the contract, the landlord can file a “Rent Determination Lawsuit” to request the judge to determine the rent amount. However, until this lawsuit is concluded, the tenant can continue to pay the amount specified in the contract (or the last amount actually paid).

Retroactive Difference Claim: The 6th Civil Chamber of the Court of Cassation (E. 2012/6440) ruled that as long as a rent determination lawsuit has not been filed, a rent difference cannot be demanded retroactively by applying an index “as if a determination judgment existed”.

Conclusion: According to court decisions; if the rent increase rate is not specified in a 5-year lease agreement, the tenant’s good-faith increase in line with the CPI rate for the first 2 years does not create an obligation to increase it in the 3rd year. Since the increase condition is not “specific and definite”, the tenant has the right to continue paying the last paid amount in the 3rd year without an increase. The landlord cannot initiate enforcement proceedings or demand eviction for the unpaid increase difference; however, they can file a rent determination lawsuit for future periods.

Why is Expert Legal Support Necessary in Rent Increase Disputes?

The complete absence of a specified increase rate or its regulation with vague expressions in a lease agreement is among the most frequent causes of disputes in practice. Supreme Court precedents mandate that in each specific case, it must be separately assessed whether the increase condition is specific and definite, whether the tenant’s previous payment behaviors have legal consequences, and whether the conditions for default have been met.

The most common mistakes in practice are; assuming that voluntary increases made by the tenant in the past create a permanent obligation, initiating enforcement proceedings despite the absence of an increase clause in the contract, and demanding an increase without filing a rent determination lawsuit. Such errors can lead to the dismissal of filed lawsuits, the cancellation of enforcement proceedings, and significant loss of rights.

Especially in regions with high tenant turnover such as Tuzla, Pendik, Kartal, Maltepe, Gebze, and Çayırova, disputes regarding rent increases are frequently brought to court. Tuzla 2M Hukuk Avukatlık Law Office provides strategic and results-oriented legal support in line with Supreme Court practices for rent increase, rent determination lawsuits, and eviction disputes arising from default. Expert legal assistance is of great importance to prevent loss of rights for both tenants and landlords.