Undeclared employees may demand from ZUS to confirm they are covered by social insurance

Lack of written contract or lack of notification to Social Insurance Institution (ZUS) does not exclude from social insurance coverage. If an employee has been hired illegally, he may apply to ZUS for a given benefit, e.g. sickness benefit. ZUS will have to determine whether an employment relationship has actually been concluded. –  Łukasz Chruściel comments for Dziennik Gazeta Prawna.

Article: here.