Policy for sales executive if he /she generate sales less then salary then Only 50% salary would be released

Hi , I have to make Policy for sales executive if he /she generate sales less then salary then Only 50% salary would be release for that month.
so this kind of policy i have to make... Actually i am not understanding what to and and what title i can give for policy. Kindly need your suggestions.

That type of policy is not supported legally