Key legal question
Whether the cantonal court had to join the affected brokers before deciding on the AHV contribution status
Extracted holding
Yes. Because the contribution decision directly affected the employees' procedural rights, they had to be joined or the matter had to be remitted so the administration could properly serve them.
Extracted reasoning
A contribution assessment on paritarian contributions determines both employer and employee obligations. Under Art. 49 ATSG, affected persons are entitled to service of the decision. The indirect forwarding through the employer was insufficient, and the cantonal court also failed to include them in the proceedings.