This article provides a detailed legal guide on all aspects of reinstatement lawsuits in Türkiye, specifically focusing on Law No. 4857 on Labor Law and current Supreme Court rulings. It covers the conditions for filing a lawsuit, mandatory mediation, grounds for termination, severance calculations, and Social Security Institution (“SSI”) notifications. The aim is to comprehensively address the rights of employees whose employment contracts are terminated by the employer for invalid reasons and the obligations of the employer throughout the entire process.

1. Employment Security and the Fundamentals of Reinstatement Lawsuits

A reinstatement lawsuit is a declaratory action filed by an employee whose employment contract has been terminated by the employer without a valid reason, or with an alleged reason deemed invalid by the employee. Its primary purpose is to seek a determination that the termination is invalid and to reinstate the employee to their job. This type of lawsuit, a cornerstone of Turkish labor law, reflects the employee's constitutional right to work. The main objective of the lawsuit is not to provide monetary gain to the employee, but rather to ensure the continuity of the employment relationship and prevent the employer from exercising their right to terminate arbitrarily.

This fundamental objective highlights the lawsuit's unique (sui generis) nature. A reinstatement lawsuit is not merely a claim for receivables; therefore, it cannot be sought together with other employee receivables such as severance pay. The ultimate goal of the lawsuit is to nullify an unjustly determined termination and re-establish the employment relationship as if the termination never occurred. This explains why the Supreme Court meticulously examines the parties' intentions throughout the process under the "sincerity" principle. Whether the employee's request to return to work and the employer's invitation to work genuinely aim to re-establish the employment relationship plays a decisive role in the outcome of the lawsuit.

2. The Concept of Employment Security and Legal Basis

The concept of "employment security" underlies the reinstatement lawsuit. Employment security is a legal protection mechanism that restricts an employer's right to terminate an indefinite-term employment contract, making this right conditional on the existence of valid reasons specified in the law. The legal framework for this security is outlined in Articles 18, 19, 20, and 21 of Labor Law No. 4857. These articles respectively regulate:

• Article 18: Conditions for benefiting from employment security and valid grounds for termination.
• Article 19: Procedure for termination notice.
• Article 20: Objection to termination notice and the lawsuit process.
• Article 21: Legal and financial consequences of termination made for an invalid reason.

These provisions aim to protect employees from arbitrary terminations by employers, fostering stability and continuity in the employment relationship.

3. Conditions for Filing a Reinstatement Lawsuit

For an employee to benefit from employment security provisions and file a reinstatement lawsuit, they must cumulatively meet all the conditions specified in the law. The absence of even one of these conditions will lead to the lawsuit being dismissed without an examination of its merits.

• 3.1. Legal Coverage: Working Under the Labor Law or Press Labor Law

The right to file a reinstatement lawsuit is primarily granted to employees working under Labor Law No. 4857 or Press Labor Law No. 5953. Employees working under the Maritime Labor Law or the Turkish Code of Obligations cannot benefit from this special protection.

• 3.2. Requirement of Working Under an Indefinite-Term Employment Contract

Employment security provisions apply only to employees working under an indefinite-term employment contract. Fixed-term employment contracts are those made under objective conditions, such as the completion of a specific task or the occurrence of a specific event, with a predetermined duration. However, the Supreme Court interprets this rule in favor of the employee. Fixed-term employment contracts that are successively (chained) without an objective reason are considered indefinite-term from the outset, and employees in such situations can benefit from employment security. In practice, the title "fixed-term" in the contract alone is not sufficient; the court may examine the nature of the work and the true intention of the parties to determine that the contract is, in fact, indefinite-term.

• 3.3. Requirement of at Least 30 Employees in the Workplace and its Calculation

To benefit from employment security, there must be 30 or more employees employed at the employer's workplace on the date the termination notice is served to the employee. The Supreme Court's broad interpretation of this number is very important:

• "Same Business Line" Criterion: When calculating the 30-employee threshold, not only the branch or unit where the termination occurred is considered, but also the total number of employees working in all of the employer's workplaces across Türkiye within the same business line (e.g., retail, banking). This interpretation extends protection to employees working in small branches of large chain businesses operating nationwide.
• Included and Excluded Employees: All employees, whether working under indefinite-term or fixed-term contracts, full-time or part-time, permanent or seasonal, are included in this number. However, apprentices, interns, and subcontractor employees are generally not included in this calculation. Nevertheless, if the employer deceptively (collusively) presents their employees under a subcontractor to avoid employment security provisions, these employees will also be considered in the 30-employee count.
• Group Companies and "Joint Employment": The Supreme Court applies the concept of "joint employment" in cases involving group companies that have an organic link, are organized under the same management, and utilize common services (e.g., accounting, security, cleaning). In such cases, when calculating the 30-employee threshold, the total number of relevant employees in all companies serving a common purpose, not just the company the employee is formally linked to, may be taken into account.

This approach reflects the principle of "substance over form" in labor law. The Supreme Court aims to prevent employers from circumventing protective legal provisions by using legal structures. Therefore, it is essential for parties to focus not only on the text of the law but also on the Supreme Court's protective interpretive approach.

• 3.4. Requirement of at Least Six Months of Seniority and its Calculation

The employee must have worked for the same employer for a period of at least six months (seniority) on the date of termination of the employment contract. The following points are considered when calculating this period:

• The probationary period stipulated in the employment contract is included in the six-month seniority period.
• The employee's intermittent work at different workplaces of the same employer is combined.
• Periods where the employment contract was suspended, such as unpaid leave, are also taken into account for seniority calculation.
• Exception: The six-month seniority requirement is not sought for employees working in underground jobs.
• 3.5. Criterion of Not Being an Employer Representative or Assistant

The last paragraph of Article 18 of the Labor Law excludes certain categories of senior managers from the scope of employment security. However, the Supreme Court interprets this exception very narrowly and establishes two distinct categories:

• Employer representatives (e.g., general managers) and their assistants (e.g., assistant general managers) who manage and direct the entire enterprise.
• Employer representatives (e.g., a factory manager meeting certain conditions) who manage and direct the entire workplace and have the sole authority to hire and dismiss employees.

The critical factor in this distinction is not the person's title, but their actual duties and authorities. If a manager's decision to hire or dismiss requires the approval or signature of another senior manager, this person is not considered to have sole authority and benefits from employment security provisions.

4. Termination Process and Validity Review

An employer's termination of an employment contract is subject to a series of rules, both procedural and substantive. Failure to comply with any of these rules is sufficient for the termination to be deemed invalid.

• 4.1. Employer's Termination Procedure Obligations: The Importance of Formal Requirements

In the termination process, procedure is as important as the reason for termination. An employer's missed step at this stage can lead to the invalidity of the termination, regardless of how justified the reason may be. This makes the situation almost a "procedural minefield" for employers.

• Written Notice Requirement: The termination notice must be made in writing in accordance with Article 19 of the Labor Law. Oral termination is invalid for an employee covered by employment security.
• Clear and Specific Stating of Termination Reason: The employer must clearly and specifically state the reason for termination in the termination notice, leaving no room for doubt. General and abstract statements such as "poor performance," "inefficiency," or "failure to comply with workplace rules" are not sufficient on their own.
• Obligation to Obtain Defense: If the termination is based on the employee's conduct or productivity, it is an absolute necessity to obtain the employee's defense regarding the matter before termination. Termination made without obtaining defense will be deemed invalid without any further examination. The only exception to this rule is immediate terminations made for just causes listed in Article 25/II of the Labor Law, such as violations of ethical and good faith rules.
• 4.2. "Termination as a Last Resort (Ultima Ratio)" Principle

Although not explicitly regulated in the Labor Law, the principle of "termination as a last resort", derived from the spirit of the law and Supreme Court precedents, is one of the most fundamental elements of a valid termination. According to this principle, before terminating an employee's employment contract, the employer is obligated to explore all alternatives that are milder and aim to maintain the employment relationship. These alternatives include:

• Issuing a warning to the employee.
• Providing vocational training to the employee.
• Changing working conditions with the employee's consent.
• If available, assigning the employee to another suitable position in the workplace.
• In case of termination due to operational reasons, measures such as eliminating overtime.

The employer must prove that termination was unavoidable and that no other alternative remained.

5. Detailed Examination of Valid Grounds for Termination

Valid grounds for termination, while not as severe as just cause for termination, are reasons that significantly and reasonably unacceptably affect the continuation of the employment relationship for the employer.

• 5.1. Reasons Arising from the Employee's Competence and Performance

This category covers situations where the employee fails to perform their work obligations at the expected level, either qualitatively or quantitatively. However, for a performance-based termination to be deemed valid, the Supreme Court requires extremely strict and objective criteria:

• Objective Evaluation: There must be a concrete, measurable, and objective performance evaluation system in place at the workplace.
• Realistic Goals: The goals given to the employee must be reasonable and achievable.
• Prior Notification: Performance standards and evaluation criteria must have been communicated to the employee in advance.
• Continuity: Performance decline should not be momentary or temporary, but should show a certain continuity.
• Training and Warning: Employees with low performance should be warned to improve their situation and, if necessary, offered training opportunities.
• Defense: As stated above, the employee's defense must be obtained.
• 5.2. Reasons Arising from the Employee's Conduct

These reasons involve the employee's culpable breach of their obligations arising from the employment contract, and this situation negatively affects the workplace order and peace. Common examples found in Supreme Court rulings include frequent tardiness, performing duties inadequately or poorly, constant and serious friction with colleagues, and failure to comply with the employer's legitimate and lawful instructions. In such terminations, it is generally expected that the employee is given a warning before termination to allow them to correct their behavior.

• 5.3. Reasons Arising from the Requirements of the Enterprise, Workplace, or Work (Operational Reasons)

Decisions made by the employer as a necessity of business management that reduce the need for labor fall into this category. For example, economic crisis, decrease in orders, certain positions becoming redundant due to technological innovations, restructuring, or the closure of a part of the workplace are operational reasons. For such a termination to be valid, the employer's decision must not be arbitrary, must be consistently applied, and must necessitate the termination.

• 5.4. Legally Invalid Grounds for Termination

Article 18 of the Labor Law explicitly states that some reasons can under no circumstances constitute a valid ground for termination. These situations constitute a violation of the employer's obligation of equal treatment and fundamental rights:

• Union membership or participation in union activities.
• Discrimination based on race, color, sex, marital status, family responsibilities, pregnancy, childbirth, religion, political opinion, and similar reasons.
• Applying to administrative or judicial authorities to seek rights arising from legislation or contract.
• Temporary absenteeism due to illness or accident within the waiting period stipulated by law.

6. Judicial Process

The reinstatement process is regulated by very strict and short "preclusion" (hak düşürücü) periods that can lead to loss of rights. Missing these deadlines will result in the irretrievable loss of the right. Therefore, seeking professional legal assistance immediately from the moment of termination is vital.

• 6.1. Mandatory Mediation as a Condition for Lawsuit

With Law No. 7036 on Labor Courts, applying to a mediator before filing a lawsuit has become a "condition for lawsuit" in reinstatement claims. A lawsuit filed without first applying to a mediator will be dismissed on procedural grounds without examining its merits.

• Application Period: The employee must apply to a mediator within one month from the date of notification of the termination of their employment contract. This period is of a preclusive nature, meaning that if missed, the right to file a lawsuit is completely lost. The term "one month" refers to a calendar month and should not be calculated as "30 days"; for example, for a notification made on February 15th, the deadline is March 15th.
• Process Flow: The mediator is required to conclude the process normally within three weeks from the date of their appointment, extending it for a maximum of one more week in mandatory circumstances, for a total of four weeks. Prescription and preclusive periods cease to run (are suspended) from the date of application to the mediation office until the date the final report is drawn up.
• Outcome: If the parties reach an agreement in mediation, the agreement document has the force of a court judgment. If an agreement is not reached, this is recorded in an "unagreement final report".
• 6.2. Filing the Lawsuit

Upon the unsuccessful conclusion of the mediation process, the way is open for the employee to file a lawsuit.

• Lawsuit Filing Period: The employee must file a reinstatement lawsuit in the labor court within two weeks from the date the mediation unagreement final report is drawn up. This two-week period is also of a preclusive nature, and if missed, the right to sue is lost.
• Competent Court: The competent courts for these lawsuits are the Labor Courts. In places where there is no Labor Court, the Civil Court of First Instance hears the case "in its capacity as a labor court."
• Authorized Court: The court of the defendant's (employer's) place of residence at the time the lawsuit is filed, or the court of the place where the work was performed, is authorized.
• 6.3. Trial Procedure and Burden of Proof Distribution

Reinstatement lawsuits are subject to the "simple trial procedure" and must be heard expeditiously by law, in order to be concluded faster.

• Employer's Burden of Proof: As a rule, the burden of proving that the termination was based on a valid reason rests with the employer. The employer must prove with concrete evidence both that the termination notice was properly issued and that the reason for termination was lawful and valid.
• Employee's Burden of Proof: If the employee claims that the termination was based on a reason different from the one stated by the employer (e.g., a union-related reason or discrimination), the burden of proving this specific claim falls on them.

7. Legal Consequences of a Reinstatement Decision

Once the court rules that the termination is invalid and that the employee should be reinstated, a new legal process and mutual obligations begin for the parties. Taking the correct steps at this stage is critical for the successful outcome of the case to have practical effect.

• 7.1. Employee's Application to Start Work After the Decision

After the court decision becomes final, the ball is now in the employee's court. The employee is obligated to apply to the employer to start work within 10 business days from the date the finalized court or private arbitration decision is served to them. This period is also preclusive; an employee who fails to apply within this period is deemed to have accepted the termination as valid, even if they won the lawsuit. In this case, the employee loses both their right to return to work and all financial rights awarded in the court decision, such as the idle period wage and non-reinstatement compensation. For ease of proof, it is strongly recommended that this application be made by notary public through a warning letter.

• 7.2. Employer's Elective Right and the "Sincerity" Principle

Upon the employee's timely application, the employer must reinstate the employee within one month. At this point, the employer has an elective right:

• Reinstates the employee.
• Does not reinstate the employee and bears the financial consequences determined by the court.

The Supreme Court subjects both parties' conduct at this stage to a "sincerity" review within the framework of the good faith rule of Article 2 of the Civil Code. The employee's application must genuinely intend to return to work, and the employer's invitation to work must be a genuine offer of reinstatement, not containing deceptive or impossible conditions.

8. Financial Consequences of a Reinstatement Decision

A reinstatement decision has two main financial consequences: idle period wage and non-reinstatement compensation.

• 8.1. Idle Period Wage (Maximum 4 Months)

Whether or not the employee is reinstated by the employer, they are entitled to their wages and other rights accrued for the period they were not employed, up to a maximum of four months, from the date the decision regarding the invalidity of the termination becomes final.

• Scope: This receivable covers the employee's gross wage along with measurable and continuous fringe benefits such as bonuses, food allowance, travel allowance, and heating allowance (adjusted gross wage). However, payments dependent on actual work, such as overtime pay or premiums, are not included in this calculation.
• Calculation: The calculation is made based on current values, taking into account comparable employee wages or wage increases in the period following the termination.
• Working Elsewhere: The employee's having worked in another workplace during this four-month period does not prevent them from claiming this receivable.
• 8.2. Non-Reinstatement Compensation (Employment Security Compensation)

If the employer does not reinstate the employee who applied on time within one month, they become obligated to pay the employment security compensation determined by the court in its decision.

• Amount: This compensation is set at an amount between at least four and at most eight months' wages of the employee.
• Criteria for Determination: Although there is no clear criterion in the law, the established precedents of the Supreme Court use the employee's seniority as the primary criterion for determining the amount of compensation. Additionally, the reason for termination (e.g., if it was due to union-related reasons) can also influence the compensation to be determined closer to the upper limit. The Supreme Court's actual practice is as follows:

Seniority Period	Generally Determined Compensation Rate (in Monthly Wages)
6 months - 5 years	4 months
5 years - 15 years	5 months
15 years and over	6 months (Can be increased up to 8 months depending on the severity of the termination reason)

9. Status of Previously Paid Severance and Notice Pay

The acceptance of a reinstatement lawsuit means that the initial termination was invalid, rendering the previously paid severance and notice pay without legal basis.

10. Post-Decision Administrative Obligations: SSI and Tax Practices

The implementation of a reinstatement decision does not only create a financial relationship between the employee and the employer; it also imposes significant administrative and financial obligations on the employer towards the state. Failure to fulfill these obligations accurately and on time can expose the employer to additional administrative fines.

• 10.1. SSI Notifications

In cases where the employee is not reinstated, the employer must make the following notifications to the Social Security Institution (SSI):

• Notification Regarding the Idle Period: The employer must retrospectively prepare and submit an "monthly premium and service document" to the SSI for the maximum 4-month idle period and pay the premiums for this period. This four-month period is added to the employee's service period.
• Updating the Employee Separation Declaration: The employee separation declaration submitted on the initial termination date becomes invalid. The employer must cancel this declaration and issue a new, updated employee separation declaration with the new termination date, which is the end of the 4-month idle period.
• Notification Periods: According to SSI Circulars, if these notifications are made within the legal period (generally by the end of the month following the month in which the employee's application was served to the employer), no administrative fine is imposed.
• Employee's Failure to Apply: If the employee fails to apply to start work within the legal 10 business days, the initial termination becomes valid. In this case, the employer has no obligation to make any retrospective SSI notifications or pay premiums.
• 10.2. Tax and Premium Deductions

Tax and premium deductions vary according to the nature of the payments made:

• Idle Period Wage: This payment is considered "wage" and is therefore subject to income tax, stamp tax, and all social security branch premiums (employee and employer shares).
• Non-Reinstatement Compensation: This payment is considered "compensation". Therefore, it is exempt from income tax and SSI premium deductions; it is only subject to stamp tax.

11. Conclusion

The reinstatement lawsuit process involves stages that require careful management and critical deadlines for both the employee and the employer.

• 11.1. Checklist for the Employee
• Definitely document the notification date of the termination notice.
• Apply to a mediator within the 1-month preclusive period from the date of notification.
• File the lawsuit within the 2-week preclusive period from the date of the mediation unagreement report.
• Apply to the employer through a notary public within the 10-business day preclusive period from the notification of the finalized court decision.
• 11.2. Checklist for the Employer
• Before termination, ensure that the termination is based on a valid reason and that the "last resort" principle has been followed.
• Fully comply with procedural requirements such as making the termination notice in writing, clearly stating the reason, and (if necessary) obtaining the employee's defense.
• Respond to the employee's timely application within 1 month (reinstatement or non-reinstatement).
• If a non-reinstatement decision is made, correctly calculate the idle period wage, non-reinstatement compensation, and difference in severance/notice pay.
• Make SSI notifications fully within the legal periods.