One of the most frequently encountered types of disputes in practice concerning the effective implementation of the right to social security, as guaranteed under Article 60 of the Constitution of the Republic of Türkiye, relates to service determination claims. The primary reason such disputes arise is, in most cases, the employer’s failure (either total or partial) to notify insured employment in order to avoid financial liabilities.
In such circumstances, employees initiate service determination lawsuits to establish periods during which they were de facto employed but which were not reflected in the records of the Social Security Institution (SSI), in other words, periods of unregistered employment.
One of the most debated issues in service determination cases concerns the allocation of the burden of proof. Owing to the distinctive nature of social security law, these proceedings do not merely concern the individual interests of the parties; they also implicate public order and public interest.
This approach has been consistently emphasized in the jurisprudence of the Court of Cassation. Given their public-order character, service determination cases are subject to an evidentiary regime that differs from that applied in ordinary private law disputes.
This study examines, in light of Court of Cassation practice, whether the burden of proof in service determination lawsuits rests with the employee or the employer.
Service determination lawsuits constitute a crucial legal mechanism for insured persons and their beneficiaries in combating undeclared employment. Through such proceedings, periods of employment not recorded by the Social Security Institution are established by court judgment and subsequently registered as insured service periods before the SSI.
In addition, the Institution may exercise its authority to collect outstanding premium receivables that remain within the applicable statute of limitations.
The statutory basis of service determination lawsuits is set forth in Article 86/9 of the Social Insurance and General Health Insurance Law No. 5510, which provides:
“Insured persons whose monthly premium and service documents or withholding and premium service declarations have not been submitted by the employer, or whose employment cannot otherwise be determined by the Institution, may apply to the labour court within five years as of the end of the year in which the services were rendered. If they prove their employment by obtaining a court judgment, the total monthly earnings and the number of premium payment days specified in the judgment shall be taken into account.”
By its legal nature, a service determination lawsuit is an action for declaratory relief. This type of action aims not only to safeguard the interests of the insured person but also to protect the interests of the Social Security Institution. Its objective is to place individuals whose insured employment has not been reported, or has been underreported, in the same legal position as those whose premiums have been duly and timely paid. In this way, the insured person’s rights and obligations are determined in accordance with the factual reality.
In service determination proceedings, the claimant may be the insured individual, his or her beneficiaries, or a trade union. The defendant is the employer. The Social Security Institution, whose rights and obligations are directly affected by the outcome of the case, participates in the proceedings as an intervening party.
With respect to the principal employer–subcontractor relationship, Article 12/6 of Law No. 5510 is determinative. Pursuant to this provision, a subcontractor is defined as a third party who undertakes work related to the production of goods or services carried out at the workplace, or in a section or ancillary part thereof, and who employs insured persons for that purpose. Even if the insured persons are recruited through the intermediary of a third party and conclude their employment contracts with the subcontractor, this does not eliminate the liability of the principal employer. In terms of the obligations imposed on the employer under the Law, the principal employer and the subcontractor are jointly liable.
Accordingly, both the principal employer and the subcontractor must be named as defendants in a service determination lawsuit.
As regards procedural requirements, the general conditions applicable in civil proceedings apply. However, although certain employee–employer disputes are subject to mandatory mediation prior to filing a lawsuit, such a requirement does not apply to service determination cases. Likewise, prior application to the Social Security Institution is not a prerequisite for filing suit. Article 4 of the Labour Courts Act No. 7036 does not provide otherwise.
Since the core issue in service determination lawsuits is the existence of insured employment, it is necessary to examine the employment contract, which constitutes the legal basis of insured status. The principal element distinguishing an employment contract from other contracts for the performance of work is the element of subordination.
Subordination refers to the employee’s performance of work under a certain degree of dependence upon the employer. This dependence encompasses the execution of work under the employer’s management, supervision, and control. The employee performs his or her duties in accordance with the employer’s instructions and, in this context, assumes a duty of obedience. This is also reflected in Article 399 of the Turkish Code of Obligations.
According to the prevailing view in legal doctrine, the element of subordination in an employment contract should be understood not as technical or economic dependence, but as personal and legal dependence. This interpretation has likewise been consistently upheld in the settled case law of the Court of Cassation.
In its decision merits no: 2016/1909 and decision no: 2020/194, the General Assembly of Civil Chambers of the Court of Cassation held:
“The criterion that characterizes an employment contract is legal-personal subordination. The feature distinguishing an employment contract from other contracts for the performance of work, both in Turkish law and in Continental European systems, is that the employee performs his work in a subordinate manner to the employer and operates within the employer’s organizational structure under a hierarchical bond. Economic and technological developments surrounding labour law have rendered the concept of subordination less distinct (Doğan, Sevil: The Element of Subordination in the Employment Contract, İzmir 2016, p. 19). Genuine legal subordination entails the employee’s obligation to comply with the execution of the work and with workplace instructions. The content of the element of subordination in an employment contract consists of acting in accordance with the employer’s instructions and the employer’s supervision of the work process and its results. Subordination is the defining characteristic of the employment contract and, in general terms, refers to legal dependence, meaning that the employee works for a definite or indefinite period under the employer’s instructions and supervision.”
One of the distinctive characteristics of service determination lawsuits is their connection with public order. This characteristic directly affects procedural rules. Accordingly, the “principle of disposition” and the “principle that the parties bring forward the facts and evidence,” which ordinarily govern civil procedure, are not applied rigidly in such cases.
As a natural consequence, the principle of ex officio investigation, whereby the court is empowered to conduct its own inquiries to ascertain the material truth finds broad application. The court is not confined to the evidence submitted by the parties and may undertake any investigation it deems necessary.
Moreover, the prohibition on the amendment or expansion of claims and defenses does not apply in the classical sense in these proceedings. The purpose of the trial is not merely to evaluate the facts alleged by the parties, but to determine the existence of insured employment in accordance with reality.
The Court of Cassation has consistently emphasized that courts are under an obligation to conduct ex officio investigations in service determination cases and to collect evidence comprehensively and on their own initiative.
In its decision merits no: 2022/11734 and decision no: 2022/13556, the 10th Civil Chamber of the Court of Cassation stated:
“… Lawsuits concerning the determination of services of persons employed under an employment contract by one or more employers relate to public order. For this reason, they must be conducted with particular sensitivity and diligence. In order to prevent loss of rights and the acquisition of insurance periods contrary to the truth, and to safeguard the right to social security, which is among fundamental human rights, courts must not confine themselves to the evidence submitted by the parties, but must conduct the necessary investigations ex officio and collect the relevant evidence.”
Pursuant to Article 190 of the Code of Civil Procedure No. 6100, the burden of proof rests with the party who derives a legal benefit from the alleged fact. Under this general rule, since the claimant in a service determination lawsuit seeks to derive a legal benefit from the determination, it would ordinarily follow that the burden of proving the existence of employment lies with the employee.
However, the specific nature of service determination cases prevents the absolute application of this classical approach. Written documents capable of demonstrating the existence of an employment relationship—such as payroll records, attendance sheets, notifications made to the Social Security Institution, and similar documentation—are typically within the sphere of control of the employer. Expecting the employee to procure and submit such evidence may not always be consistent with the ordinary course of life.
Accordingly, the employer is required to submit to the court all records and documents in its possession relating to whether the employee worked. Thus, while the burden of proof appears, in theory, to rest with the employee, in practical terms the employer’s obligation to produce documents and provide explanations becomes predominant.
Furthermore, given the public-order character of service determination lawsuits, the principle that the parties bring forward the facts is not applied strictly, and the court is under an obligation to conduct an ex officio investigation. In seeking to establish the material truth, the court may rely not only on documentary evidence but also on witness testimony.
It is particularly important, in terms of evidentiary value, that witnesses be selected from among individuals who were actually employed at the workplace during the period in which the claimant alleges having worked and whose employment was duly reported to the Social Security Institution. Nevertheless, where witness testimony relates to events occurring in the distant past, judicial authorities tend to approach such statements with caution and often attribute limited weight to them.
In addition, testimony from owners or employees of neighboring workplaces operating in proximity to the defendant’s workplace may also be taken into consideration. The Court of Cassation has repeatedly underlined the necessity of conducting a comprehensive investigation in service determination cases and of evaluating statements from surrounding witnesses.
In its decision merits no: 2015/1622 (Merits) and decision no: 2019/196, the General Assembly of Civil Chambers held:
“… In such cases, it must first be investigated, in due form, whether documents relating to the claimant’s employment were submitted by the employer. If this condition is met, it must then be determined comprehensively whether the workplace actually existed and whether it fell within the scope of the Law or was of a nature to be included within such scope. Thereafter, the existence of the employment relationship must be examined with particular sensitivity. Although the fact of employment may be proven by any kind of evidence, witness statements must be evaluated with regard to the nature of the work, as well as the commencement and termination dates. Care must be taken to select witnesses who worked at the same workplace during the same period as the claimant and whose employment was officially recorded in the employer’s payroll, or employees of neighboring employers whose names appear in official records. The fact of employment must be established through these testimonies in a manner that leaves no room for doubt or hesitation.”
Within this framework, it is evident that the general rule concerning the burden of proof under Article 190 of the Code of Civil Procedure No. 6100 is not applied in a rigid manner in service determination lawsuits. In other words, the classical procedural principle that “the party asserting a claim must prove it” is rendered flexible due to the unique character of these proceedings.
Since such cases are subject to the simplified procedure and concern public order, the court bears an obligation to conduct an ex officio investigation. This makes it legally difficult to attribute the burden of proof exclusively to one party.
Judicial practice has likewise adopted this approach. The settled jurisprudence of the Court of Cassation clearly affirms that, in service determination cases, the burden of proof cannot be assessed in a unilateral and absolute manner.
In its decision merits no: 2015/3943 and decision no: 2019/509 the General Assembly of Civil Chambers stated:
“Since lawsuits concerning the commencement date of insured status and the determination of services relate to public order and, according to the settled case law of the Court of Cassation, must therefore be conducted with particular sensitivity and diligence, the judge in service determination cases, which concern public order, must demonstrate special care, collect evidence ex officio, and render a decision accordingly. In such cases where the principle of ex officio investigation applies, the burden of proof cannot be imposed upon a single party.”