4.   Assessment:

(1)   After the close of the year for which returns have been submitted by an importer, who is a dealer under rule 3 or in the course of the year, where an importer has discontinued business, the assessing authority shall, if he is satisfied after such scrutiny of the accounts and making such enquiry as he considers necessary that the returns filed are correct and complete, finally assess in a single order on the basis of the return, the tax payable for the year to which the return relate.

(2)   Where any such importer-fails to submit return or returns before the date prescribed in that behalf or  if any return or returns submitted by him appears to be incorrect or incomplete to the assessing authority, the assessing authority shall after giving the dealer an opportunity, determine the value of goods to the best of his judgment and finally assess in a single order the tax payable.

(3)   If on final assessment under sub-rule(1) or sub-rule(2), any tax is found to be due from the importer after deducting the tax or taxes paid by him towards the provisional assessment made under rule 3, the assessing authority shall serve on the importer a notice in Form D-2, and the dealer shall pay the sum demanded in the notice therein. if any refund of tax is found to be due to the dealer, the assessing authority shall serve on him a notice in Form R.