"SECTION 91. Payment of Tax. -

"(A) Time of Payment. - The estate tax imposed by Section 84 shall be paid at the time the return is filed by the executor, administrator or the heirs.

"(B) Extension of Time. - When the Commissioner finds that the payment on the due date of the estate tax or of any part thereof would impose undue hardship upon the estate or any of the heirs, he may extend the time for payment of such tax or any part thereof not to exceed five (5) years, in case the estate is settled through the courts, or two (2) years in case the estate is settled extrajudicially. In such case, the amount in respect of which the extension is granted shall be paid on or before the date of the expiration of the period of the extension, and the running of the Statute of Limitations for assessment as provided in Section 203 of this Code shall be suspended for the period of any such extension.

"Where the taxes are assessed by reason of negligence, intentional disregard of rules and regulations, or fraud on the part of the taxpayer, no extension will be granted by the Commissioner.

"If an extension is granted, the Commissioner may require the executor, or administrator, or beneficiary, as the case may be, to furnish a bond in such amount, not exceeding double the amount of the tax and with such sureties as the Commissioner deems necessary, conditioned upon the payment of the said tax in accordance with the terms of the extension.

"(C) Liability for Payment. - The estate tax imposed by Section 84 shall be paid by the executor or administrator before delivery to any beneficiary of his distributive share of the estate. Such beneficiary shall, to the extent of his distributive share of the estate, be subsidiarily liable for the payment of such portion of the estate tax as his distributive share bears to the value of the total net estate.

"For the purpose of this Chapter, the term 'executor' or 'administrator' means the executor or administrator of the decedent, or if there is no executor or administrator appointed, qualified, and acting within the Philippines, then any person in actual or constructive possession of any property of the decedent.