Your employee falls under the social security insurance schemes of the Netherlands
Social security regulation No. 883/2004, social security agreements or national legislations determine whether your employee falls under the social security insurance schemes of the Netherlands. If this is the case, you are required to pay the Dutch employed persons' insurance contributions. You also pay the employer's contribution pursuant to the Health Care Insurance Act (Zvw) or withhold the contribution pursuant to the Health Care Insurance Act (Zvw).
When you are under the obligation to act as a withholding agent you must also withhold the national insurance contributions.