Assessment-

(1) If the prescribed authority is satisfied that any return submitted under sub-section (3) of section 5 and sub-section (1) of section 5A is correct and complete, it shall assess the proprietor on the basis thereof. (2) If no return is submitted by the proprietor under sub-section (3) of section 5 and sub-section (1) of section 5A within the period prescribed or if the return submitted by him appears to be incorrect or incomplete, the prescribed authority shall, after making such enquiry as it considers necessary, determine the tax due under all or any of the provisions of sections 4, 4A and 6A and assess the proprietor to the best of its judgment. Provided that before taking action under this sub-section, the proprietor shall be given a reasonable opportunity of proving the correctness and completeness of any return submitted by him or that no return was due from him. (3) The assessment made under this section shall subject to any order in appeal or revision be final.