Introduction

Electronic signatures in Turkish law are governed by Law No. 5070 on Electronic Signatures, published in the Official Gazette No. 25355 dated January 23, 2004. The law's central proposition is simple: a "secure electronic signature" produces the same legal consequences as a handwritten signature. In recent years, the digitalization of commercial practice and especially the normalization of remote work have accelerated the widespread use of electronic signatures in institutional contract workflows. However, the practical implementation of electronic signatures does not mean that its legal effect is guaranteed in every circumstance; both the type of contract and the nature of the signature must be considered.

In this article, we address the secure electronic signature regime introduced by Law No. 5070, in which contracts it may be used, the force of electronically signed documents in the law of evidence under the Code of Civil Procedure (HMK), and the points to be observed in institutional practice in commercial operations.

Law No. 5070: Four Types of Signatures

The law does not address the signature from a single category; it addresses it from multiple layers. Each layer has different legal effects.

Simple electronic signature

Electronic data added to any electronic data or logically linked to electronic data. For example, a name or full name written at the end of an email. Its legal effect is limited; it does not independently carry the evidentiary force provided by a secure electronic signature.

Secure electronic signature

The most important category under the law. A signature is a secure electronic signature when it meets the following four conditions:

Being exclusively linked to the signatory,
Having been created with a secure electronic signature creation tool that is solely in the control of the signatory,
Establishing the identity of the signatory on the basis of a qualified electronic certificate,
Enabling the detection of any subsequent alterations to the signed electronic data.

In Turkey, qualified electronic certificates are produced by Electronic Certificate Service Providers (ECSP)—such as authorized entities including TÜBİTAK BİLGEM Public SM, E-Tuğra, and E-Güven. Secure electronic signatures may be used with tools such as smart cards, USB tokens, or mobile signatures.

Mobile signature

A type of secure electronic signature applied through a GSM SIM card; provided by operators. Its legal effect is equivalent to that of a secure electronic signature.

KEP and e-correspondence

Registered Electronic Mail (KEP) is a message delivery system established with a secure electronic signature. Sending a discharge, notice of default, or notification via KEP is reliable evidence for proving delivery.

Law of Evidence: HMK Article 205/2

The main legal force of a secure electronic signature is embodied in HMK Article 205/2: "Electronic data created in accordance with the rules by means of a secure electronic signature shall have the force of a deed." This provision produces two fundamental consequences:

Force as a deed: Data signed with a secure electronic signature possesses the evidentiary force of written evidence. It is accepted as admissible evidence in disputes where proof by witness testimony is prohibited.
Burden of proof to the contrary: The party denying the signature bears the burden of proving otherwise. The electronic equivalent of signature examination, which is resorted to in classical handwritten signature denial, is certificate verification plus timestamp examination.

HMK Article 210 supplementarily regulates how evidence shall operate with respect to electronic evidence. Decisions of the Supreme Court of Appeals have also confirmed in numerous rulings that electronically signed documents are accepted as equivalent to documents signed with wet ink signatures.

Which Contracts May Be Executed with Electronic Signatures?

Article 5/2 of Law No. 5070 lists in a limited manner the transactions in which secure electronic signatures may not be used. All written transactions outside this limited list may be executed with secure electronic signatures.

Transactions closed to electronic signatures

Transactions subject to official formality: Real property sales contracts (at the land registry office), marriage, promise of gift, promise of real property, and other transactions that must be performed in the presence of a land registry officer or notary,
Bank guarantee letters (except those issued by insurance companies established in Turkey),
Surety contracts (according to the law's current form; however, in commercial practice this exception has been debated from time to time, and according to the current text of the law, suretyship must be written by hand and signed),
Other transactions for which the law requires a special form requirement.

Typical commercial contracts open to electronic signatures

Goods and service supply contracts,
SaaS, software license, hosting contracts,
Distributorship, agency, and dealership agreements,
Non-disclosure agreements (NDA) and data processing agreements (DPA),
Employee employment contracts—provided that care is taken with respect to certain special employee rights (certain types of discharge that require handwriting by the employee),
Purchase orders and delivery reports,
Electronic commerce user agreements,
Payment contracts (including customer agreements within the framework of Law No. 6493).

Relation to Foreign Signatures: eIDAS and Foreign Certificates

The legal force of electronic signatures in Turkey is tied to the qualified certificate produced by Turkish ESCPs. Signatures affixed with certificates produced by a foreign ECSP (for example, CAs used by Adobe Sign, DocuSign CAs) do not automatically meet the definition of "qualified certificate" in Law No. 5070.

In this case:

The electronically signed document with a foreign certificate is deemed a simple electronic signature,
It does not automatically acquire the force of a deed under HMK Article 205/2,
However, it may be evaluated as evidence; the court assigns value according to the specific circumstances of the case.

If Turkish companies are executing contracts with foreign counterparties using electronic signatures; the Turkish party signing with secure electronic signature, the counterparty signing with wet ink signature or local equivalent certificate, or a hybrid solution may be achieved. Alternatively, signatures made on foreign DocuSign/Adobe Sign platforms are evaluated together with an explicit "we accept electronic signatures between us" clause added by the parties to the contract.

On the EU side, the eIDAS Regulation (910/2014) ensures mutual recognition of qualified electronic signatures throughout the EU; however, mutual recognition comparable to eIDAS between Turkey and the EU does not yet exist.

Points to Be Observed in Institutional Practice

1. Authentication and authorization

A mechanism for documenting that the person affixing the signature is authorized to represent the company and that the signature is affixed on behalf of the company is essential. Since the e-signature is linked to a personal certificate, the basis for corporate signature authority must additionally be established (for example, signature circulars, board of directors resolutions).

2. Certificate management

Qualified certificates have an expiration period (typically 1-3 years). Signing with an expired certificate may render the signature controversial. A management procedure is required in the institution to track which persons may use which certificates and until when.

3. Timestamp

A timestamp service must be used to be able to prove that a document has not been altered "since a certain date." A qualified timestamp is the reliable time source contemplated by Law No. 5070 and plays a critical role in evidence.

4. Archiving

For long-term preservation of electronically signed documents, archiving protocols—long-term digital archive (LTA)—are required that allow the signature to be verified even after the certificate has expired. This is particularly important for documents with longer retention periods, such as commercial ledgers, tax records, and contracts.

5. Explicit reference to electronic signatures in the contract

Including a clause in the contract that explicitly states the parties accept electronic signatures strengthens the legal ground in case of a potential dispute. This clause is particularly necessary in contracts signed with foreign counterparties or foreign certificates.

6. Use of KEP for notices and declarations

KEP is superior to physical mail for notices of default, termination notices, statements of claim, or declarations in terms of proving delivery. Transferring official correspondence to KEP in institutional practice provides both speed and evidentiary force.

Typical Scenarios in Disputes

Electronic signature disputes in practice may be grouped under three typical scenarios:

Scenario 1 – Denial: One party claims that the signature was not affixed by him or her. In secure electronic signatures, the burden of proof shifts to the denier. Negligence in certificate management (use of another's USB token, PIN sharing) may strengthen the denial.

Scenario 2 – Foreign certificate: One party has signed with a qualified certificate in Turkey, and the other has signed with a foreign provider. The court evaluates based on the acceptance clause in the contract and the concrete force of the evidence.

Scenario 3 – Certificate expiration: It is subsequently determined that the certificate had expired on the contract date. The legal force of the signature becomes controversial; if a timestamp exists, the moment of signing may be proven.

Conclusion

Although secure electronic signature was enacted in 2004, it took many years to become fully established in Turkish commercial practice. Today, digitalized contract workflows, remote work, and cross-border business collaborations have transformed e-signatures from a convenience tool into a strategic practice.

The modern version of institutional contract architecture is one that plans in advance which signature type will be used for which contract, establishes certificate management and archiving as an operational discipline, and is prepared for hybrid solutions in dealings with foreign counterparties. When this discipline is established, electronic signatures not only provide speed and cost advantages; they provide concrete evidentiary force that strengthens one's legal position in disputes.

Electronic Signatures in Commercial Contracts and Evidentiary Force