What Happens If the Lease Has No Rent Increase Clause?

What Happens If the Lease Has No Rent Increase Clause? How Is the Rent Increase Calculated?

Under Turkish law, increasing the rent is not a matter left entirely to the free will of the parties. Articles 343 through 346 of Turkish Code of Obligations No. 6098 ("the Code") surround rent-related provisions in residential and roofed workplace leases with limits rooted in public policy. In practice, the question that comes up most often is this: if a lease contains no rent increase clause, is the landlord required to increase the rent, is the landlord even entitled to do so, and if so, through what procedure and at what rate? This article addresses these questions in light of current legislation and Court of Cassation case law.

I. The General Framework: The Exception to the Ban on Changing Lease Terms

Article 343 of the Code permits a change to the detriment of the tenant in exactly one respect:

"No change may be made to the detriment of the tenant in lease agreements, other than the determination of the rent." — Turkish Code of Obligations No. 6098 (Official Gazette: 4 February 2011, adopted 11 January 2011), Art. 343

The natural consequence of this rule is that no lease term other than the rent itself — a security deposit, a late-payment penalty, an early-termination fee, and the like — may be made more burdensome to the tenant's detriment, whether unilaterally or through renewal. Increasing the rent is the sole exception the law allows, but it is itself bound by strict procedural and rate limits.

II. Does the Lease Contain a Rent Increase Clause? Why the Distinction Matters

Article 344 of the Code sets out two different regimes depending on whether the parties have agreed on an increase.

A. Where the Lease Contains a Rent Increase Clause (Art. 344/1)

"The parties' agreement as to the rent to apply in renewed lease periods is valid provided it does not exceed the rate of change in the twelve-month average of the consumer price index for the preceding rental year. This rule also applies to lease agreements with a term of more than one year." — Turkish Code of Obligations No. 6098, Art. 344/1

If the lease fixes a specific increase rate (for example, "15%" or "the CPI rate"), that rate is valid as long as it does not exceed the twelve-month average change in the CPI. If the contractual rate exceeds that ceiling, the applicable rate is reduced to the CPI average; if the contractual rate is below the ceiling, the (lower) contractual rate applies. The Court of Cassation's 3rd Civil Chamber has consistently applied this same calculation discipline in its recent decisions (Court of Cassation 3rd Civil Chamber, Case No. 2025/6193, Decision No. 2026/2965, dated 12.05.2026).

B. Where the Lease Contains No Rent Increase Clause (Art. 344/2)

This is the situation this article is chiefly concerned with:

"Where the parties have not reached an agreement on this matter, the rent — provided it does not exceed the rate of change in the twelve-month average of the consumer price index for the preceding rental year — is determined by the judge on equitable grounds, having regard to the condition of the leased property." — Turkish Code of Obligations No. 6098, Art. 344/2

As this shows, where a lease contains no increase clause, the law ties the increase not to a unilateral declaration by either party, but either to a new agreement between the parties or to a determination by the judge.

III. "Am I Required to Increase the Rent?"

If the lease contains no increase clause, the landlord is under no obligation to raise the rent; increasing it is a right for the landlord, not a duty. If the landlord never exercises that right, the lease simply continues at the previous rent — this produces no adverse consequence for the landlord.

If, however, the landlord does wish to claim an increase, that claim is only valid if it follows a specific procedure and timeline. A common misconception at this point is the belief that, in a lease with no increase clause, the landlord may claim an increase at any time, at any rate, and with retroactive effect. The settled case law of the Court of Cassation's 6th Civil Chamber says otherwise:

"For rent to be claimed from the beginning of the period for which its determination is sought, either the lease must contain an increase clause, or, in accordance with Article 345 of Law No. 6098 as in force on the date the action is filed, a written notice concerning the rent increase must have been given to the tenant no later than thirty days before the start of the rental period for which determination is sought, or the action must have been filed within that same thirty-day period; in either case the action must be filed by the end of the following new rental period." — Court of Cassation 6th Civil Chamber, Case No. 2015/11442, Decision No. 2016/37, dated 18.01.2016 (see also Case No. 2014/12566, Decision No. 2015/9235, dated 02.11.2015)

The same Chamber has reaffirmed this principle more recently, holding that, in a lease with no increase clause, the conditions for adaptation of the rent must be examined (Court of Cassation 3rd Civil Chamber, Case No. 2025/2638, Decision No. 2025/3932, dated 09.09.2025). The upshot: if the landlord claims an increase without meeting these timing and procedural requirements, the increase claim is rejected for that particular period — but this does not bar the landlord from making a fresh, timely claim for the following rental period.

IV. How Is the Rent Increased? Procedure and Time Limits

Where a lease contains no increase clause, the rent may be increased through the following routes:

1. Agreement between the parties for the new period. The tenant and the landlord are free to agree on a rent for the new period that does not exceed the CPI ceiling. This is the simplest and least contentious route.

2. Timely written notice or a court action. If no agreement is reached, Article 345 of the Code comes into play:

"An action for the determination of the rent may be brought at any time. However, where the action is filed no later than thirty days before the start of the new rental period, or the landlord has given the tenant written notice within that period that the rent will be increased, and the action is filed by the end of the following new rental period, the rent determined by the court binds the tenant from the start of that new rental period." — Turkish Code of Obligations No. 6098, Art. 345/1-2

In practice, this means the landlord must either (i) send the tenant a formal written notice of the rent increase claim no later than thirty days before the new period begins, or (ii) file a rent-determination action directly within that same period. Once either condition is met, the rent the court determines applies from the start of the period even if the action itself is filed later, up to the end of the following rental period.

3. Mandatory mediation. Under Article 18/B of the Mediation in Civil Disputes Law No. 6325 — added by Article 37 of Law No. 7445 — since 1 September 2023, applying to a mediator before filing suit is a precondition for any dispute arising from a lease relationship, with the exception of eviction proceedings through execution without a judgment (ilamsız tahliye). This means the mediation process must be completed before a rent-determination action is filed; note that applying for mediation does not suspend the thirty-day period under Article 345 of the Code, so the timing of the process needs to be planned accordingly.

Whether disputes over the determination of rent for residential and roofed workplace leases may be submitted to arbitration remains debated, but the General Assembly of Civil Chambers of the Court of Cassation has recently held, irrespective of the nature of the leased property, that such disputes arising out of lease agreements may be capable of arbitration (General Assembly of Civil Chambers, Case No. 2025/502, Decision No. 2026/15, dated 21.01.2026).

V. What Is the Rent Increase Rate? How the CPI Calculation Works

The benchmark used both for the contractual increase ceiling and for the rent the judge determines is the rate of change in the twelve-month average of the CPI (Consumer Price Index). This rate is announced by the Turkish Statistical Institute (TÜİK) in the first week of every month, based on the data for the month immediately preceding the month in which the increase is to take effect.

For example, according to the August 2026 data TÜİK announced on 3 September 2026, the twelve-month average change in the CPI came in at 31.79%; this rate sets the ceiling applicable to lease periods renewing in September 2026. Because the rate changes every month, current data should be checked against TÜİK's official statistics pages.

A historical note: under Provisional Article 1 (added to Law No. 6098 by Law No. 7409) and Provisional Article 2 (added by Law No. 7456), a fixed 25% increase ceiling applied, exceptionally, to residential leases renewing between 8 June 2022 and 1 July 2024. That temporary arrangement has since expired, and today the twelve-month CPI average again applies to both residential and roofed workplace leases.

The five-year rule. Regardless of whether the parties have reached an agreement, in leases with a term longer than five years, or renewed after five years, and at the end of every subsequent five-year period, the rent is redetermined by the judge on equitable grounds, taking into account the CPI rate together with the condition of the leased property and comparable rental values (Art. 344/3 of the Code). In that scenario the CPI ceiling is no longer applied on its own but becomes part of a broader "equity" assessment together with comparable rents; the Court of Cassation has consistently held that the CPI ceiling may be exceeded in these periods (Court of Cassation 3rd Civil Chamber, Case No. 2026/113, Decision No. 2026/3228, dated 20.05.2026; Case No. 2026/1213, Decision No. 2026/1751, dated 30.03.2026).

Rent denominated in foreign currency. If the rent is fixed in the lease in a foreign currency, subject to the provisions of Law No. 1567 on the Protection of the Value of Turkish Currency, no change may be made to the rent before five years have passed; the excessive-hardship provision of Article 138 of the Code is the exception to this rule (Art. 344/4 of the Code).

VI. Conclusion

The absence of a rent increase clause in a lease does not deprive the landlord of the ability to increase the rent; exercising that ability, however, is strictly bound by the rate ceiling and the time limits set out in Articles 344 and 345 of the Code. If the landlord fails to exercise the right to an increase within the required time and procedure, the increase cannot be claimed for that particular period — but the right is not lost for subsequent periods. It should also be kept in mind that, since 2023, mandatory mediation has become part of the process as a precondition for rental disputes.

References

• Turkish Code of Obligations No. 6098, Arts. 343-346 — https://www.mevzuat.gov.tr/mevzuat?MevzuatNo=6098&MevzuatTur=1&MevzuatTertip=5

• Mediation in Civil Disputes Law No. 6325, Art. 18/B — https://www.mevzuat.gov.tr/mevzuat?MevzuatNo=6325&MevzuatTur=1&MevzuatTertip=5

• General Assembly of Civil Chambers of the Court of Cassation, Case No. 2025/502, Decision No. 2026/15, dated 21.01.2026

• Court of Cassation 3rd Civil Chamber, Case No. 2026/113, Decision No. 2026/3228, dated 20.05.2026

• Court of Cassation 3rd Civil Chamber, Case No. 2026/1213, Decision No. 2026/1751, dated 30.03.2026

• Court of Cassation 3rd Civil Chamber, Case No. 2025/6193, Decision No. 2026/2965, dated 12.05.2026

• Court of Cassation 3rd Civil Chamber, Case No. 2025/2638, Decision No. 2025/3932, dated 09.09.2025

• Court of Cassation 6th Civil Chamber, Case No. 2015/11442, Decision No. 2016/37, dated 18.01.2016

• Court of Cassation 6th Civil Chamber, Case No. 2014/12566, Decision No. 2015/9235, dated 02.11.2015

• The full text of the decisions above can be reached by their case/decision numbers through the official precedent-search systems: Court of Cassation Decision Search (https://karararama.yargitay.gov.tr/) and UYAP Precedent Search (https://emsal.uyap.gov.tr/)

• Turkish Statistical Institute (TÜİK), monthly Consumer Price Index (CPI) bulletins — https://www.tuik.gov.tr

The information in this article is based on the legislation and case law in force as of its publication date; the rate, time limits, and procedure applicable to a specific rental dispute may vary depending on the terms of the lease and the particular facts of the file. This article is for general informational purposes only and does not constitute legal advice.