The only deductions from the value of the property transferred shall be those set forth in this part. Except as otherwise provided in this article, they shall be deductible regardless of whether or not assets comprising the decedent's taxable estate are employed in the payment or discharge of the deductible items. When a tax is imposed upon a transfer described in subsection (c) of section 2107 and section 2108,¹ the deductions shall be allowed to the transferee only to the extent that the transferee has actually paid the deductible items and either the transferee was legally obligated to pay the deductible items or the estate subject to administration by a personal representative is insufficient to pay the deductible items.