It is permissible for the workplace to deduct something from the employee’s salary to pay off a debt that he owes to them, provided that that is done with the consent of both parties and provided that it will not add up to more than what is owed.

Discount coupons which are obtained in return for payment are prohibited because they involve several infractions of Islamic teachings. Free coupons that are offered to purchasers without them having to pay anything in return are permissible and there is nothing wrong with using them and benefitting from them.