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).
Invalidity of Contract: Absolute Nullity (Butlan) and Voidability
TBK m.27, m.28 and defects of intent
When is a contract invalid? Absolute nullity, voidability, defects of intent, unjust exploitation and lack of form under the Turkish Code of Obligations.
For a contract to be validly formed, the parties must have capacity, the declarations of intent must be sound, the subject matter must be possible and not contrary to law or morality, and the required form (if any) must be observed. Lack of any of these results, depending on the type of contract, either in absolute nullity or in voidability.
Absolute Nullity (Butlan) — TBK m.27
Under TBK m.27/1, contracts contrary to mandatory rules, morals, public order or personality rights, or whose subject matter is impossible, are absolutely null. Nullity operates from inception (ex tunc), does not depend on a party's request and is considered by the court of its own motion.
Partial nullity is possible: under TBK m.27/2, nullity of some clauses does not affect the validity of the others; however, if it appears clearly that the contract would not have been concluded without the void clause, the whole contract is null.
Voidability — Defects of Intent
A voidable contract is one that has validly come into being but allows the party whose intent is defective to declare, within a defined period, that it does not consider itself bound. Mistake (hata), fraud (hile) and duress (ikrah), regulated in TBK m.30 et seq., are grounds for defect of intent.
The right to set aside based on defect of intent must be exercised within one year of learning of the defect or of the cessation of the effect of duress (TBK m.39). The period is one of forfeiture; lapse confirms the contract and it remains in force.
Unjust Exploitation (Gabin) — TBK m.28
If a contract shows a clear disproportion in performances, brought about by exploiting the disadvantaged party's distress, thoughtlessness or inexperience, the injured party may, depending on the circumstances, either declare that it does not consider itself bound and demand restitution of what it gave, or remain bound and demand correction of the disproportion.
This right must be exercised within one year of learning of the thoughtlessness or inexperience (or of the cessation of the distress), and in any event within five years of contract formation.
Lack of Form and Its Consequences
Contracts concluded without the prescribed statutory form are, as a rule, absolutely null (TBK m.12/2). Promises to sell immovables (TBK m.29), construction contracts in return for share, suretyship (TBK m.583) and donations (TBK m.288) require validity forms.
Where performance has substantially been carried out, the Court of Cassation may refuse to entertain later reliance on lack of form as contrary to good faith; this exception is, however, narrowly construed.
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.27Absolute nullity (butlan) and partial nullity
Original (Turkish, official):
MADDE 27- Kanunun emredici hükümlerine, ahlaka, kamu düzenine, kişilik haklarına aykırı veya konusu imkânsız olan sözleşmeler kesin olarak hükümsüzdür. Sözleşmenin içerdiği hükümlerden bir kısmının hükümsüz olması, diğerlerinin geçerliliğini etkilemez. Ancak, bu hükümler olmaksızın sözleşmenin yapılmayacağı açıkça anlaşılırsa, sözleşmenin tamamı kesin olarak hükümsüz olur.
English summary (non-binding):
Contracts contrary to mandatory rules, morals, public order or personality rights, or whose subject matter is impossible, are absolutely null. Nullity of some provisions does not affect the validity of the others; however, if it is clear that the contract would not have been concluded without the null provisions, the whole contract is absolutely null.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.28Unjust exploitation (gabin)
Original (Turkish, official):
MADDE 28- Bir sözleşmede karşılıklı edimler arasında açık bir oransızlık varsa, bu oransızlık, zarar görenin zor durumda kalmasından veya düşüncesizliğinden ya da deneyimsizliğinden yararlanılmak suretiyle gerçekleştirildiği takdirde, zarar gören, durumun özelliğine göre ya sözleşme ile bağlı olmadığını diğer tarafa bildirerek ediminin geri verilmesini ya da sözleşmeye bağlı kalarak edimler arasındaki oransızlığın giderilmesini isteyebilir. Zarar gören bu hakkını, düşüncesizlik veya deneyimsizliğini öğrendiği; zor durumda kalmada ise, bu durumun ortadan kalktığı tarihten başlayarak bir yıl ve her hâlde sözleşmenin kurulduğu tarihten başlayarak beş yıl içinde kullanabilir.
English summary (non-binding):
Where the mutual performances of a contract show a clear disproportion brought about by exploiting the injured party's distress, thoughtlessness or inexperience, the injured party may — depending on the circumstances — either declare not being bound and demand restitution of what was given, or remain bound and demand correction of the disproportion. The right must be exercised within one year of learning of the thoughtlessness or inexperience (or of cessation of the distress), and in any case within five years of contract formation.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.30Mistake (hata)
Original (Turkish, official):
MADDE 30- Sözleşme kurulurken esaslı yanılmaya düşen taraf, sözleşme ile bağlı olmaz.
English summary (non-binding):
A party who, on conclusion of the contract, is under an essential mistake is not bound by the contract.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.36Fraud (hile)
Original (Turkish, official):
MADDE 36- Taraflardan biri, diğerinin aldatması sonucu bir sözleşme yapmışsa, yanılması esaslı olmasa bile, sözleşmeyle bağlı değildir. Üçüncü bir kişinin aldatması sonucu bir sözleşme yapan taraf, sözleşmenin yapıldığı sırada karşı tarafın aldatmayı bilmesi veya bilecek durumda olması hâlinde, sözleşmeyle bağlı değildir.
English summary (non-binding):
A party who has been induced to conclude a contract by the other party's fraud is not bound, even where the mistake is not essential. A party induced by a third party's fraud is not bound where the other party knew or ought to have known of the fraud at the time of contract.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.37Duress (ikrah)
Original (Turkish, official):
MADDE 37- Taraflardan biri, diğerinin veya üçüncü bir kişinin korkutması sonucu bir sözleşme yapmışsa, sözleşmeyle bağlı değildir. Korkutan bir üçüncü kişi olup da diğer taraf korkutmayı bilmiyorsa veya bilecek durumda değilse, sözleşmeyle bağlı kalmak istemeyen korkutulan, hakkaniyet gerektiriyorsa, diğer tarafa tazminat ödemekle yükümlüdür.
English summary (non-binding):
A party who has concluded a contract as a result of duress by the other party or a third party is not bound. Where the duress is by a third party and the other party did not know and could not have known, the threatened party who wishes to be released is, where equity so requires, obliged to compensate the other party.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.39Exercise of the right to set aside — one-year forfeiture
Original (Turkish, official):
MADDE 39- Yanılma veya aldatma sebebiyle ya da korkutulma sonucunda sözleşme yapan taraf, yanılma veya aldatmayı öğrendiği ya da korkutmanın etkisinin ortadan kalktığı andan başlayarak bir yıl içinde sözleşme ile bağlı olmadığını bildirmez veya verdiği şeyi geri istemezse, sözleşmeyi onamış sayılır. Aldatma veya korkutmadan dolayı bağlayıcılığı olmayan bir sözleşmenin onanmış sayılması, tazminat hakkını ortadan kaldırmaz.
English summary (non-binding):
A party who has concluded a contract by mistake, fraud or duress and, within one year of learning of the mistake or fraud or of cessation of the effect of duress, has neither declared non-binding effect nor demanded restitution of what was given, is deemed to have ratified the contract. Such deemed ratification of a contract not binding by reason of fraud or duress does not exclude the right to damages.
Source: mevzuat.gov.tr · last reviewed: 2026-05-12
- TBK m.12Freedom of form and its exceptions
Original (Turkish, official):
MADDE 12- Sözleşmelerin geçerliliği, kanunda aksi öngörülmedikçe, hiçbir şekle bağlı değildir. Kanunda sözleşmeler için öngörülen şekil, kural olarak geçerlilik şeklidir. Öngörülen şekle uyulmaksızın kurulan sözleşmeler hüküm doğurmaz.
English summary (non-binding):
Unless statute provides otherwise, the validity of contracts is not subject to any form. Forms prescribed by statute are, as a rule, validity forms; contracts concluded in disregard of the prescribed form produce no effect.
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
The distinction between absolute nullity and voidability determines the available claims and the applicable periods. Letting the one-year voidability period lapse may irreversibly cure a legally defective contract.
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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