The insured person and any person in Australia acting on behalf of the insurer shall be the agents of the insurer, and shall be jointly and severally liable as such for all purposes of this Act. If either of those persons pays or credits to the insurer any amount in respect of the insurance contract before arrangements have been made to the satisfaction of the Commissioner for the payment of any income tax which has been or may be assessed under this Division in respect of that amount, that person shall be personally liable to pay that tax.