Turkish law requires companies established in Turkey to use Turkish language in all of their transactions, contracts, correspondences, accounts and records, pursuant to a code titled “Law 805 pertaining to the Mandatory Use of Turkish in Commercial Enterprises (İktisadi Müesseselerde Mecburi Türkçe Kullanılması Hakkında Kanun, No: 805)” dated 1926, which is still in force.

Article 1 of this law states that all Turkish companies shall use Turkish language in all of their transactions, contracts, correspondences, accounts and records.

Article 2 of this law states that foreign companies shall use Turkish in their correspondences with public authorities in Turkey and their correspondences with Turkish companies and individuals in Turkey.

Article 3 states that if another language is used as translation besides Turkish in a document, the Turkish version will prevail.

Article 4 states that companies not conforming to this obligation cannot enforce their rights pursuant to foreign language documents.

Article 7 provides the legal consequence of nonconformity with the legal obligation of using Turkish language in commercial dealings: upon complaint of related persons, a public prosecution shall be commenced against the companies not conforming to this legal obligation. The court may rule for a day-fine of a minimum of 100 days worth of net income.

Furthermore, there are supreme court decisions enforcing the law in question. Two such decisions are summarized below.

In a 2009 Supreme Court decision the Court did not allow a company to exert its claims relying on a contract in a foreign language, which contracted was executed by a Turkish bank and a Turkish customer, in which the bank stated the reason for drafting the contract in English was that they intended to send it to their branch in Bahrain. The Court deemed the documents in a foreign language void (even though signed by the parties) citing Articles 1 and 4 of the Law No:805 (11 HD, 2009/2051 E. 2009/5292 K. 04.05.2009 T.).

In a 2012 Supreme Court decision overruled a local court decision, and asserted that an agreement entered into by two Turkish companies shall be void if not made in Turkish. The agreement even stipulated ICC arbitration in London. Even so, the Supreme Court applied the principle of geographical limitation, and ruled that as long as the agreement or correspondence is performed within Turkey, the Turkish language requirement would apply. (11 HD, 2012/3122 E. 2012/4073 K. 16.03.2012 T.)

In conclusion, in order for a contract or correspondence involving a Turkish company to be valid from the perspective of said Turkish company, such documents should be written in Turkish or translated into Turkish. Otherwise such agreement or correspondence may be be deemed null and void.