"SECTION 62. Exemption Allowed to Estates and Trusts. - For the purpose of the tax provided for in this Title, there shall be allowed an exemption of Twenty thousand pesos (P20,000) from the income of the estate or trust.

"SECTION 63. Revocable Trusts. - Where at any time the power to revest in the grantor title to any part of the corpus of the trust is vested (1) in the grantor either alone or in conjunction with any person not having a substantial adverse interest in the disposition of such part of the corpus or the income therefrom, or (2) in any person not having a substantial adverse interest in the disposition of such part of the corpus or the income therefrom, the income of such part of the trust shall be included in computing the taxable income of the grantor.

"SECTION 64. Income for Benefit of Grantor. -

"(A) Where any part of the income of a trust (1) is, or in the discretion of the grantor or of any person not having a substantial adverse interest in the disposition of such part of the income may be held or accumulated for future distribution to the grantor; or (2) may, or in the discretion of the grantor or of any person not having a substantial adverse interest in the disposition of such part of the income, be distributed to the grantor; or (3) is, or in the discretion of the grantor or of any person not having a substantial adverse interest in the disposition of such part of the income may be applied to the payment of premiums upon policies of insurance on the life of the grantor, such part of the income of the trust shall be included in computing the taxable income of the grantor.

"(B) As used in this Section, the term 'in the discretion of the grantor' means in the discretion of the grantor, either alone or in conjunction with any person not having a substantial adverse interest in the disposition of the part of the income in question.