(a) A tax required to be paid by a trustee based on receipts allocated to income must be paid from income.
(b) A tax required to be paid by a trustee based on receipts allocated to principal must be paid from principal, even if the tax is called an income tax by the taxing authority.
(c) A tax required to be paid by a trustee on the trust's share of an entity's taxable income must be paid:
(1) From income to the extent that receipts from the entity are allocated only to income;