Section 4
SEC. 4. Section 51 (a) of the National Internal Revenue Code of 1977, as amended, is hereby further amended by adding thereto a new Subparagraph (4), prescribing the manner of payment of the tax imposed on capital gains to read as follows: "(4) Payment of Capital Gains Tax.—The total amount of tax imposed under Section 34 (g) and (h) shall be paid on the date the return prescribed therefor is filed by the person liable thereto: Provided, however, That if the seller submits proof of his intention to avail himself of the benefit of exemption of capital gains under existing special laws, no such payment shall be required; Provided, further, That in case of failure to qualify for exemption under such special laws and implementing rules, the tax due on the gains realized from the original transaction shall immediately become due and payable, and subject to the penalties prescribed under applicable provisions of this Code; and Provided, finally, That if the seller, having paid the tax, submits such proof of intent within six months from the registration of the document transferring real property, he shall be entitled to a refund of such tax upon verification of his compliance with the requirements for such exemption. "In case the person elects and is qualified to report the gain by installments under Section 43 of this Code, the tax due from each installment payment shall be paid within thirty (30) days from the receipt of such payments."