Section 4(6) in Punjab General Sales Tax (Deferment and Exemption) Rules, 1991
(6)The unit shall have the option to avail the benefit of either deferment of, or exemption from, the liability to pay tax under the Act:Provided that such an option shall be exercised in Form ST(D&E) VIII within thirty days from the date of the issue of the final notification or from the date of issue of the eligibility certificate, as the case may be, and the option once exercised shall be final.
