If the employee has a written employment contract requiring that he or she be paid within the pay scale, then the company must honor that contract and increase the employee's pay if the scale increases. If the employer does not, the employee could sue for "breach of contract" to enforce the terms of the contract and get the extra money.But if there is no such written contract, the pay scale is just the company's voluntary and freely adopted guidelines for pay; it is not enforceable, and the employer may ignore it at will and would not have to increase the employee's pay.