In a grantor trust, the grantor (e.g., the creator of the trust or a person who made a gratuitous transfer to the trust) must report on her personal income tax return all items of income, loss, deduction and credit attributable to the portion of the trust which she is deemed to own under the grantor trust rules of Sections 671 – 679 of the Internal Revenue Code (the Code). This is straightforward when the trust is treated as wholly-owned by a single grantor. But when multiple grantors are treated as owners of different portions of the trust (a "multiple-grantor trust"), how should those grantors divide the income of the trust among themselves? Treasury Reg. Section 1.671-3 provides three possibilities for how ownership could be determined: by a fractional share (the "fractional approach"), by a pecuniary amount, or by tracing specific property (the "specific property approach"). However, Reg. Section 1.671-3 is generally drafted from the perspective of a single grantor who is treated as owner with respect to a portion of the trust. The regulations do not provide clear guidance as to how to determine the ownership of a multiple-grantor trust, and it is not certain the circumstances in which the IRS or a court would view each of these approaches as the more (or only) appropriate method for determining how income should be allocated among grantors.