Payment of tax in lump.

1[3-A. Payment of tax in lump.—Notwithstanding anything contained in section 3 an owner may, in lieu of tax chargeable under the Act opt to pay by way of composition such sum of money the lump sum as may be determined from time to time by the Government with reference to the seating capacity of Motor Vehicle and notified by it : Provided that nothing contained in this section shall apply to an owner owning more than one motor vehicle unless he exercises such option in respect of all such vehicles liable to tax.