A secondment (in Dutch, detachering) is a temporary arrangement under which an employee is placed to work at or for a different entity, while the original employment contract with the home employer remains active throughout. The home employer continues to pay salary, remains responsible for social-security contributions, and retains the employment relationship. A secondment agreement between the home and host entity documents the terms, cost recharging, and duration.
An international assignment, by contrast, can take a broader range of legal forms. At one end, the assignment mirrors a secondment with the home contract preserved. At the other end, the home contract is suspended or terminated and a new host-country contract is executed, shifting the employment relationship and many compliance obligations to the host entity. Hybrid structures also exist, combining a suspended home contract with a fixed-term host contract.
The structural choice affects which entity bears payroll, social-security, and immigration obligations. Under the EU Posted Workers Directive, a seconded employee retains home-country social security (with an A1 certificate) for up to 24 months. If the arrangement exceeds that threshold or the home contract is replaced, the analysis changes materially. Legal counsel in both the home and host countries should review the structure before the arrangement begins.