6. (1) Every person who keeps a motor vehicle for use shall fill up and sign a declaration in the prescribed form stating truly the prescribed particulars and shall deliver the declaration as so filled up and signed to the Taxing Officer and shall pay to the Taxing Officer the Tax which he appears by such declaration to be liable to pay in respect of such vehicle.(2) Where a motor vehicle is altered so as to render the person who keeps such vehicle for use liable to the payment of an additional tax under section 7, such person shall fill up and sign an additional declaration, in the prescribed form showing the nature of the alterations made and containing the prescribed particulars and shall deliver such additional declaration as so filled up and signed to the Taxing Officer and shall pay to the Taxing Officer the additional tax payable under section 7 which he appears by such additional declaration to be liable to pay in respect of such vehicle. (3) Every person who owns any motor vehicle which is let for hire otherwise than on a hire-purchase agreement shall, for the purposes of this Act, be deemed to be the person who keeps such vehicle for use.