Title II — TAX ON INCOME (c) and 28(B)(5)(c) shall be paid on the date the return prescribed therefor is filed by the person liable thereto: Provided, 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 payments shall be required: Provided, further, That in case of failure to qualify for exemption under such special laws and implementing rules and regulations, 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: Provided, finally, That if the seller, having paid the tax, submits such proof of intent within six (6) months from the registration of the document transferring the 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 taxpayer elects and is qualified to report the gain by installments under Section 49 of this Code, the tax due from each installment payment shall be paid within thirty (30) days from the receipt of such payments. No registration of any document transferring real property shall be effected by the Register of Deeds unless the Commissioner or his duly authorized representative has certified that such transfer has been reported, and the tax herein imposed, if any, has been paid. (B) Assessment and Payment of Deficiency Tax. — After the return is filed, the Commissioner shall examine it and assess the correct amount of the tax. The tax or deficiency income tax so discovered shall be paid upon notice and demand from the Commissioner. As used in this Chapter, in respect of a tax imposed by this Title, the term ‘deficiency’ means: (1) The amount by which the tax imposed by this Title exceeds the amount shown as the tax by the taxpayer upon his return; but the amount so shown on the return shall be increased by the amounts previously assessed (or collected without assessment) as a deficiency, and decreased by the amount previously abated, credited, returned or otherwise repaid in respect of such tax; or (2) If no amount is shown as the tax by the taxpayer upon his return, or if no return is made by the taxpayer, then the amount by which the tax exceeds the amounts previously assessed (or collected without assessment) as a deficiency; but such amounts previously assessed or collected without assessment shall first be decreased by the amounts 82 Isla Lipana & Co., the Philippine member firm of the PwC network