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Time Opens? Conditions, Periods and Critical Differences within the Scope of Turkish Code of Obligations Articles 344, 345 and 138. This guide has been updated as of 2026, based on the Turkish Code of Obligations No. 6098 and the compulsory mediation regulation in Law No. 7445.
Summary A rent determination lawsuit is filed to redetermine the current rent based on comparable market values; As a rule, 5 years must pass since the contract and a lawsuit or a warning must be filed at least 30 days before the new term. A lease adaptation lawsuit can be filed at any time, without any time limit, in the event of an unforeseen extraordinary development after the contract is established. The mandatory mediation process must be exhausted before either lawsuit is filed.
Two Different Cases, Two Different Stories A landlord whose rent is well below market value and a tenant who is unable to pay his rent in an unexpected crisis must actually resort to two completely different legal remedies. These two cases are often confused, and going to court with the wrong type of case can result in a process that takes years to be dismissed from the start.
In this guide, the conditions, opening times and basic differences between the rent determination case and the rent adjustment case are discussed.
What is a Rent Determination Case? A rent determination case is a type of case that allows the judge to re-determine the current rent for the new rent period, taking into account the location, qualities and comparable market values of the real estate. Its legal basis is Articles 344 and 345 of the Turkish Code of Obligations.
In order for the lawsuit to be filed, there must be a valid and ongoing residential or roofed workplace lease agreement between the parties. In accordance with the third paragraph of Article 344 of the Law, determination of the new rental fee may be requested in lease agreements with a duration of more than 5 years or renewed after 5 years. In the case filed within the first 5 years, the judge determines an increase not to exceed the twelve-month average rate of change in the consumer price index. In cases filed after five years, this limit is eliminated and the determination is made directly according to current precedent values by applying an equity discount.
As a rule, a rent determination lawsuit can be filed at any time; However, in order for the lawsuit to have an impact on the new period, it must be filed at least 30 days before the beginning of the new period or a written warning must be notified to the tenant by the property owner that the increase will be made within this period. If this condition is met, the new price determined by the court will be valid from the first day of the new period; Otherwise, the case becomes valid for the next rental period.
What is a Lease Adjustment Case? A lease adaptation lawsuit is filed to adapt the contract to new conditions in case of radical developments that the parties could not foresee and that would violate the rule of honesty after the conclusion of the contract. Its legal basis is Article 138 of the Turkish Code of Obligations, which regulates the difficulty of excessive performance.
Four conditions are required for a lawsuit to be filed: the emergence of an extraordinary situation (such as economic crisis, pandemic, natural disaster) that did not exist when the contract was made; It is not possible to foresee this situation when signing the contract; Due to changing conditions, the party's performance reaches a level that violates the rule of honesty; and the party whose rights have been damaged has not yet fulfilled its debt or has paid it with a reservation stating "I reserve my rights". The adaptation request of the party that continues to pay unconditionally is weakened.
There is no waiting period in the rent adjustment case as in the determination case. If extraordinary and unforeseen circumstances occur even in the first month of the contract, a lawsuit can be filed immediately; It is not subject to any periodic calendar or notice requirement.
Basis Time Condition As a rule, 5 years must pass from the contract. It can be opened at any time, there is no period requirement. Justification: The rental price is below or above the market rate. Unforeseen extraordinary events. If the conditions are complied with, it is valid from the beginning of the new period. From the date of the lawsuit, sometimes from the beginning of the crisis.
Case Summary: Rent Determination Case Ahmet Bey rented his flat in Kadıköy for 5,000 TL per month in 2021. With legal increases over the years, the rent increased to 12,000 TL in 2026, but the current rent for comparable apartments in the same building has increased to 40,000 TL.
Legal Evaluation: Since the 5-year period in the contract has expired, Mr. Ahmet has the right to file a rent determination lawsuit without being subject to the legal CPI limit. The court examines the precedents and applies an equity reduction and increases the rent to an amount close to the current market value.
Case Summary: Lease Adjustment Case A tourism company rented a large guest complex for a high annual fee. Two months after the contract, an unforeseen radical administrative decision or an extraordinary development occurred that completely affected the region and the operation of the business stopped.
Legal Evaluation The company cannot be expected to pay this rent according to the rule of honesty. Even if the contract has not expired for 5 years yet, the company may file a rent adaptation lawsuit in accordance with Article 138 of the Turkish Code of Obligations and request the rent to be reduced by the court.
Mandatory Mediation Requirement In accordance with the regulation made within the scope of Law No. 7445, it is mandatory to apply to the mediation office before filing both rent determination cases and rent adaptation cases. Cases filed directly before the mediation phase is completed are rejected by the court due to procedural reasons. In addition, filing an adaptation lawsuit in a situation where a declaratory lawsuit should be filed, or vice versa, will lead to the rejection of the case and unnecessary attorney's fee liability.
Can the tenant also file a rent determination lawsuit? Yes, although rarely. Although, as a rule, the property owner files this lawsuit to increase the rent, in exceptional cases where the rent is excessively high under market conditions, the tenant may also file a declaratory lawsuit and request that the price be reduced.
If the 30-day notice period is missed, is the right to sue completely lost? No, a lawsuit can be filed at any time; However, if the period condition is not complied with, the new price determined by the court will be valid for the next rental period, not for the current period. Therefore, time tracking directly affects the magnitude of the loss.
Attention: Common Mistakes in the Process Choosing the wrong case type: Filing an adaptation case for a demand based on market value or a declaratory action for a demand based on an extraordinary crisis will lead to the rejection of the case due to procedural reasons.
Skipping the mediation stage: Filing a lawsuit directly without resorting to compulsory mediation will result in rejection due to lack of a lawsuit requirement. Payment without reservation: If a party who is considering filing an adaptation lawsuit continues to pay the rent without making any reservations, this will weaken its claim.
Conclusion Revising the rental price is a technical process that requires accurate reading of precedent values and legal calendars. Incorrect notice timing, a missed 30-day period, or an adaptation lawsuit filed hastily before the conditions are met may leave both property owners and tenants facing a long-lasting trial that results in financial loss.
Important Legal Notice: The legal explanations and case studies contained in this guide have been prepared by Küheylan Law Firm for general information purposes and do not constitute legal advice. Since the unique conditions of each contract may change the outcome, it is recommended that the process be carried out with the support of a real estate and rental law lawyer. © 2026 Küheylan Law Firm. All rights reserved.
Author: Av. Mert Deniz Küheylan Küheylan Law Firm — Burhaniye Mh. Neşetbey Sk. No:12/5 Floor:5 Flat:3 Üsküdar/İstanbul — info@kuheylan.av.tr — kuheylanhukuk.com
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