Contracts Law
This section covers the core institutions of the law of obligations — from contract formation to termination, from performance to adaptation. The articles are prepared in light of the Turkish Code of Obligations (No. 6098).
Standard Terms and Consumer Protection: The 'Unwritten' Sanction
Review of unfair terms under TBK m.20-25 and TKHK m.5
When are standard contractual clauses invalid? Standard terms, the 'unwritten' sanction and review of unfair terms in consumer contracts.
Standard clauses found in credit contracts, membership terms, insurance policies and service forms — drafted in advance by one party and presented to the other — are called 'standard terms' (genel işlem koşulları). TBK m.20-25 establishes a special review regime to protect the weaker party.
Definition and Scope — TBK m.20
Under TBK m.20, standard terms are contract provisions prepared in advance by the drafter alone, for use in a large number of similar contracts, and presented to the other party. For a provision to qualify as a standard term, it is enough that it was not individually negotiated; prior use in other contracts is not required.
Standard terms must comply with the nature of the contract, the matter and statutory rules. Review applies regardless of whether they appear in the contract document or a separate document.
'Unwritten' Sanction — TBK m.21-22
For standard terms adverse to the other party to enter the contract, three conditions must be met: (i) the drafter must, at the time of contract, expressly inform the other party of the terms; (ii) provide an opportunity to learn their content; and (iii) obtain the other party's acceptance. Failing any one of these, the standard term is deemed unwritten (TBK m.21/1).
The 'unwritten' sanction is stronger than classical invalidity: the provision is treated as never having been part of the contract. Under TBK m.22, the rest of the contract continues to be valid, and the drafter cannot claim it would not have concluded the contract without the unwritten provision.
Content Review — TBK m.25
Standard terms may not contain provisions contrary to good faith that are adverse to or aggravate the other party's position (TBK m.25). Such terms are invalid even if part of the contract.
In Court of Cassation practice, standard provisions in bank-credit contracts on file fees, mandatory life insurance, unilateral interest changes and early-repayment penalties are frequently struck down under content review.
Unfair Terms in Consumer Contracts — TKHK m.5
Article 5 of the Consumer Protection Act (No. 6502) provides stricter protection against unfair terms in consumer contracts. Terms unilaterally inserted without negotiation that, contrary to good faith, cause an imbalance to the consumer's detriment are unfair and absolutely null.
No application by the consumer is required; the court reviews ex officio. In consumer proceedings before the Consumer Arbitration Board or the Consumer Court, unfair terms may themselves form a discrete subject of dispute.
Practical Considerations
In contractual disputes, not only the signed text but also offer correspondence, revision history, invoices, delivery records, payment records, formal notices and the parties' subsequent conduct are taken into account. The formation, performance and termination of a contract often acquire meaning only through these ancillary documents.
Form requirements, authority of representation, penalty clauses, exclusion-of-liability provisions, standard terms and consumer-protection rules may all affect the validity or enforceability of a contract. In standard-form documents in particular, the other party must be informed, express acceptance obtained, and onerous provisions specifically highlighted.
Before any dispute arises, the scope of obligations, delivery date, defect notice, default notice, interest and competent-court clauses should be drafted explicitly. Vague provisions may give rise to interpretation disputes and to difficulties of proof later on.
Relevant Statutory Provisions
- TBK m.20Definition of standard terms
Original (Turkish, official):
MADDE 20- Genel işlem koşulları, bir sözleşme yapılırken düzenleyenin, ileride çok sayıdaki benzer sözleşmede kullanmak amacıyla, önceden, tek başına hazırlayarak karşı tarafa sunduğu sözleşme hükümleridir. Bu koşulların, sözleşme metninde veya ekinde yer alması, kapsamı, yazı türü ve şekli, nitelendirmede önem taşımaz. Aynı amaçla düzenlenen sözleşmelerin metinlerinin özdeş olmaması, bu sözleşmelerin içerdiği hükümlerin, genel işlem koşulu sayılmasını engellemez. Genel işlem koşulları içeren sözleşmeye veya ayrı bir sözleşmeye konulan bu koşulların her birinin tartışılarak kabul edildiğine ilişkin kayıtlar, tek başına, onları genel işlem koşulu olmaktan çıkarmaz. Genel işlem koşullarıyla ilgili hükümler, sundukları hizmetleri kanun veya yetkili makamlar tarafından verilen izinle yürütmekte olan kişi ve kuruluşların hazırladıkları sözleşmelere de, niteliklerine bakılmaksızın uygulanır.
English summary (non-binding):
Standard terms are contract provisions prepared in advance by the drafter alone, for use in a large number of similar contracts, and presented to the other party. Their location in the contract or an annex, scope, font and form are irrelevant to qualification. The fact that the texts of contracts drawn for the same purpose are not identical does not prevent their provisions from being treated as standard terms. Notations that each term has been discussed and accepted do not by themselves remove standard-term character. The provisions on standard terms also apply, regardless of their nature, to contracts prepared by persons and institutions carrying on services under permission of law or competent authority.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.21Unwritten sanction
Original (Turkish, official):
MADDE 21- Karşı tarafın menfaatine aykırı genel işlem koşullarının sözleşmenin kapsamına girmesi, sözleşmenin yapılması sırasında düzenleyenin karşı tarafa, bu koşulların varlığı hakkında açıkça bilgi verip, bunların içeriğini öğrenme imkânı sağlamasına ve karşı tarafın da bu koşulları kabul etmesine bağlıdır. Aksi takdirde, genel işlem koşulları yazılmamış sayılır. Sözleşmenin niteliğine ve işin özelliğine yabancı olan genel işlem koşulları da yazılmamış sayılır.
English summary (non-binding):
For standard terms adverse to the other party to be included in the contract, the drafter must, at the time of contract, expressly inform the other party of their existence, provide an opportunity to learn their content, and obtain the other party's acceptance. Otherwise the standard terms are deemed unwritten. Standard terms foreign to the nature of the contract and the matter are also deemed unwritten.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.22Validity of the contract apart from unwritten terms
Original (Turkish, official):
MADDE 22- Sözleşmenin yazılmamış sayılan genel işlem koşulları dışındaki hükümleri geçerliliğini korur. Bu durumda düzenleyen, yazılmamış sayılan koşullar olmasaydı diğer hükümlerle sözleşmeyi yapmayacak olduğunu ileri süremez.
English summary (non-binding):
The provisions of the contract other than the standard terms deemed unwritten remain valid. In this case, the drafter cannot claim that, without the unwritten terms, it would not have concluded the contract on the other provisions.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.23Rule of interpretation (against the drafter)
Original (Turkish, official):
MADDE 23- Genel işlem koşullarında yer alan bir hüküm, açık ve anlaşılır değilse veya birden çok anlama geliyorsa, düzenleyenin aleyhine ve karşı tarafın lehine yorumlanır.
English summary (non-binding):
A provision in standard terms that is not clear and understandable, or that bears more than one meaning, is interpreted against the drafter and in favour of the other party.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.24Prohibition of unilateral modification
Original (Turkish, official):
MADDE 24- Genel işlem koşullarının bulunduğu bir sözleşmede veya ayrı bir sözleşmede yer alan ve düzenleyene tek yanlı olarak karşı taraf aleyhine genel işlem koşulları içeren sözleşmenin bir hükmünü değiştirme ya da yeni düzenleme getirme yetkisi veren kayıtlar yazılmamış sayılır.
English summary (non-binding):
Clauses — in a contract containing standard terms or in a separate contract — granting the drafter unilateral power to modify a provision of the contract containing standard terms or introduce a new provision, to the other party's detriment, are deemed unwritten.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.25Content review
Original (Turkish, official):
MADDE 25- Genel işlem koşullarına, dürüstlük kurallarına aykırı olarak, karşı tarafın aleyhine veya onun durumunu ağırlaştırıcı nitelikte hükümler konulamaz.
English summary (non-binding):
Standard terms may not contain provisions contrary to good faith that are adverse to or aggravate the position of the other party.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TKHK m.5Unfair terms in consumer contracts
Original (Turkish, official):
MADDE 5- (1) Haksız şart; tüketiciyle müzakere edilmeden sözleşmeye dâhil edilen ve tarafların sözleşmeden doğan hak ve yükümlülüklerinde dürüstlük kuralına aykırı düşecek biçimde tüketici aleyhine dengesizliğe neden olan sözleşme şartlarıdır. (2) Tüketiciyle akdedilen sözleşmelerde yer alan haksız şartlar kesin olarak hükümsüzdür. Sözleşmenin haksız şartlar dışındaki hükümleri geçerliliğini korur. Bu durumda sözleşmeyi düzenleyen, kesin olarak hükümsüz sayılan şartlar olmasaydı diğer hükümlerle sözleşmeyi yapmayacak olduğunu ileri süremez. (3) Bir sözleşme şartı önceden hazırlanmış ve standart sözleşmede yer alması nedeniyle tüketici içeriğine etki edememişse, o sözleşme şartının tüketiciyle müzakere edilmediği kabul edilir. Sözleşmeyi düzenleyen, bir standart şartın münferiden müzakere edildiğini iddia ediyorsa bunu ispatla yükümlüdür. (4) Sözleşme şartlarının yazılı olması hâlinde, tüketicinin anlayabileceği açık ve anlaşılır bir dilin kullanılmış olması gerekir. Sözleşmede yer alan bir hükmün açık ve anlaşılır olmaması veya birden çok anlama gelmesi hâlinde; bu hüküm, tüketicinin lehine yorumlanır.
English summary (non-binding):
Unfair terms are clauses inserted into the contract without negotiation with the consumer that, contrary to good faith, create an imbalance in the parties' contractual rights and obligations to the consumer's detriment. Unfair terms in consumer contracts are absolutely null; the rest of the contract remains valid, and the drafter cannot claim it would not have concluded the contract without the null terms. A pre-formulated term included in a standard contract whose content the consumer could not influence is presumed not to have been negotiated; if the drafter claims a standard term was individually negotiated, the burden of proof lies with the drafter. Where the contract is written, the language must be clear and understandable to the consumer; a provision that is unclear or open to multiple meanings is interpreted in the consumer's favour. The provisions apply, regardless of nature, to contracts of persons and institutions operating under permission of law or competent authority. Unfairness is assessed by reference to the nature of the goods or services, the circumstances at contract formation, the other provisions of the contract, and any related contracts, as of the time of formation. Where terms are written clearly, no assessment is made of the balance between principal performances or between the market price and the agreed price. The Ministry takes measures to remove unfair terms from contracts of general use and prevent their use. Detailed rules and a non-exhaustive list of presumed unfair terms are set out in regulations.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
The statutory provisions are reproduced for information purposes only. The current and official text on mevzuat.gov.tr is authoritative.
Conclusion
Boilerplate 'I have read and understood' acknowledgements no longer provide automatic protection. Showing the standard terms to the other party and negotiating them before signing reduces the risk of later 'unwritten' findings.
This article is for information purposes only and does not constitute legal advice. If you would like professional assistance on a specific matter, you may request a consultation.
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