How to initiate a Refund

Physically Disabled employees donot need to pay Professional Tax as given in the Assam Professional Tax guidelines as given under the heading - "Exemptions for Professional Tax" of (https://www.indiafilings.com/learn/assam-professional-tax/). However if it is deducted during salary release, it should be refunded. I would like to know the process involved for this refund? What does the employee need to do for a refund of Professional Tax?