The Work Permit card is issued to the worker, and must be held by the worker at all times for proper identification.
As an employer, you must not keep the Work Permit cards of your foreign workers or foreign domestic workers.
You should also not force your workers to give you their Work Permit cards.
Likewise, workers should not ask their employers to keep their Work Permit cards for them.
Employers should provide their workers with the means to keep their Work Permit cards and other belongings securely, such as lockers, etc, with unrestricted access.
If your employer insist on keeping your Work Permit card, you can contact MOM for help.