RTC § 17742

(a) Except as otherwise provided in this chapter, the income of an estate or trust is taxable to the estate or trust. The tax applies to the entire taxable income of an estate, if the decedent was a resident, regardless of the residence of the fiduciary or beneficiary, and to the entire taxable income of a trust, if the fiduciary or beneficiary (other than a beneficiary whose interest in such trust is contingent) is a resident, regardless of the residence of the settlor.

(b) For purposes of this article the residence of a corporate fiduciary of a trust means the place where the corporation transacts the major portion of its administration of the trust.