New Rules for Determining Length of Service

As of January 1, 2026, new rules for determining an employee’s length of service have entered into force, significantly changing the previous approach to recognizing the course of professional activity. Under the new regulations, length of service includes not only periods of employment under an employment contract, but also other forms of professional activity.

These changes are relevant to both employees and employers, as they affect the scope of employee entitlements arising under labor law.

Business Activity and Mandate Contracts Included in Length of Service

The regulations in force as of 2026 provide that an employee’s length of service includes, inter alia:

• periods of conducting non-agricultural business activity,
• periods of work performed under a mandate contract (contract of mandate),
• other periods of professional activity for which social security contributions were paid.

The new rules make it possible to take into account the actual course of an individual’s professional career, regardless of the legal form under which the work was performed.

Impact of the New Rules on Employee Entitlements

The length of service has a direct impact on a number of employee entitlements. Under the applicable regulations, length of service determines, inter alia:

• the amount of annual leave,
• the length of the notice period,
• entitlement to long-service awards,
• access to other benefits that are contingent upon length of service.

In practice, this means that individuals who previously performed work under civil law contracts or conducted business activity may now take such periods into account when determining their employment-related entitlements.

Determining Length of Service Based on ZUS Data

The Social Insurance Institution (Zakład Ubezpieczeń Społecznych- ZUS) plays a key role in the application of the new regulations. Data collected within the social insurance system constitute the basis for confirming periods of professional activity that are included in an individual’s length of service.

In practice, particular importance is attached to proper registration for social insurance and to the completeness of the data submitted to ZUS, especially with respect to periods dating back many years.

Do You Have Questions Regarding the Determination of Length of Service After 2026?

The changes in force as of 2026 may give rise to questions as to how individual periods of professional activity are to be included in the calculation of length of service and how they affect employee entitlements.

Contact our experts to obtain support in interpreting the applicable regulations and to discuss their application in your specific situation.