New rules for calculating seniority – changes and obligations for employers

New regulations regarding the calculation of seniority are one of the most important changes for employers in 2026. They will introduce new obligations and have a direct impact on employment costs and recruitment processes. In the following article, we present key aspects of this reform from an employer’s perspective.

Deadlines for introducing changes – what and for whom?

According to the Act of 26 September 2025 amending the Act – Labour Code and certain other acts, the new regulations will enter into force on different dates depending on the sector:

• Public sector – the obligation to apply the new rules comes into force on 1 January 2026.
• Private sector – the regulations will come into force 6 months after their publication in the Journal of Laws (date of publication: 2025-10-21).

Regardless of the sector, periods of work from before the date of entry into force of the Act will be included in the length of service, provided they are properly documented.

What periods will be included in seniority?

According to the new regulations, the seniority will include:

• periods of conducting non-agricultural activities and cooperation with a person running a business,​​​​​
• the period of suspension of business activity by a person running a non-agricultural business activity in order to provide personal care for a child,
• periods of performance of the contract of mandate,
• provision of services, agency agreement and period of being a cooperating person,
• the period of being a member of an agricultural production cooperative and a cooperative of agricultural circles,
• a (documented) period of paid work other than employment spent abroad.

Greater employee entitlements vs. employer costs

Including additional periods of service in the new rules carries specific financial and organizational consequences for employers. From a budget and HR perspective, the following aspects are crucial:

• Increased vacation leave entitlement – longer length of service may result in an employee being granted a higher vacation entitlement sooner (e.g. from 20 to 26 days).
• Allowances and jubilee awards – where internal regulations provide for length of service allowances or jubilee awards, increased length of service may mean the need to pay higher allowances or faster acquisition of the right to the award/next level.
• Higher severance pay – length of service is often a factor influencing the amount of severance pay in the event of termination.

Remember that entitlements such as seniority bonuses or anniversary bonuses depend on the regulations in force at a given employer (collective agreement, remuneration policy). If a given employer does not offer such benefits, increasing the length of service does not generate additional costs in this regard.

Obligations and verification of seniority documentation

Employers are not obligated to automatically recalculate the length of service for all employees. The obligation to update entitlements arises in two situations:

• Presentation of documents by the employee. The employee provides documents confirming the new periods of employment (or other activity) to be included.
• Internal documents held. The employer previously employed the employee under a contract (e.g., a mandate contract), the performance of which counts towards seniority under the new regulations.

Deadlines for submitting documents by employees

Employees have a specific time to document new periods, and these deadlines depend on the sector in which the employer operates:

• Public sector: 24 months from 1 January 2026
• Private sector: 24 months from 1 May 2026

Periods not documented within these deadlines by an employee employed on the date the Act enters into force will not be included in the length of service on which employee rights depend.

The employer’s right to verification

The employer has the right to disregard a given period if the documents presented by the employee raise reasonable doubts. The final determination of periods of service is the responsibility of the employer. In the event of a dispute, a labour court will resolve the matter.

New periods included in the internship – what should you pay special attention to?

The new regulations expand the list of activities included in the length of service, which requires special attention in verification and recruitment processes.

1. Business Activity (JDG)

The employment period includes the period of non-agricultural business activity for which the employee paid contributions to retirement, disability, or accident insurance. This also includes the period of benefiting from the so-called “start-up relief,” during which the employee was not covered by retirement or disability insurance.

2. Civil Law Contracts (Mandate Contracts)

Periods of work performed under civil law contracts (e.g. contracts of mandate) are also included.

The single-period rule. If the term of a mandate contract overlaps with the term of an employment contract, only one of these periods is counted towards the seniority period. It is not possible to count seniority twice for the same calendar period.

3. Confirmation of Periods

As a rule, employment history and periods of self-employment will be confirmed by a certificate issued by the Social Insurance Institution (ZUS) (contribution payment). If the employee was not covered by social security, they must provide proof of employment (e.g., a contract with the employer).

Impact of new rules on recruitment

The new rules will apply to new recruitments for vacant positions initiated after the new regulations come into force (after 1 January 2026 in the public sector and after 1 May 2026 in the private sector).

During the qualification process, the candidate will be required to submit documents confirming all periods of employment, including those not previously taken into account, such as certificates of business activity or work under civil law contracts.

Recruitment processes that were initiated but not completed before the date of application of the new regulations will be decided according to the existing rules.

Key activities for the HR department – what are they?

In view of the entry into force of the regulations, the HR department should focus on, among others:

• Regulations Audit. Review of internal regulations (remuneration, work, Employee Benefits Fund) in terms of the definition of length of service and related benefits.
• Preparation of Procedures. Development of an internal procedure for verifying and crediting new internship periods based on documents submitted by employees.
• Internal Communications. Informing employees of their obligation to document periods and deadlines.
• Staff Training. Training HR staff on new policies and documents that need to be adopted and verified.

Preparing for these changes in advance will help avoid personnel errors, disputes with employees, and unplanned costs related to the need to equalize entitlements.

Find out how we can help: