In deciding Moore v. United States, Justice Kavanaugh discussed that what was really at issue in the case was not anything regarding unrealized income, but rather a question of attribution. In the opinion, he said Congress could choose whether to attribute taxation to the entity or to have it flow-through to the owner. At the time, it felt a bit underdeveloped as an idea. But as Alex Zhang shows in his article, The Forgotten Attribution Power, 135 Yale L. J. ___ (forthcoming 2026), this concept actually has deep roots back to the early years of the modern income tax. It also shows that even after Moore, Congress does have tools, if it wants to exercise them, to attribute income and tax some level of unrealized appreciation.

One of the first key contributions of the piece is the push toward clarity of terms. Zhang divides the terms into two major domains, constitutional and statutory. Attribution is a constitutional consideration grounded in due process. If there is some income Y, attribution asks if Congress has the power to tax A, B, or both for income Y. Assignment of income, on the other hand, is a statutory question. If Congress has the power to tax income Y to both A and B, assignment of income is who Congress assigns the tax associated with income Y between A, B, or both of them. Zhang also notes that realization as well has both constitutional dimensions as to whether Congress has the power and statutory dimensions as to how Congress wields that power. Furthermore, both the constitutional and statutory realization concepts have a conditional dimension, which looks at whether realization is required for tax to hit a taxpayer, and a content dimension, which looks at what features are required to meet the realization requirement.

Zhang then builds out the concept of attribution through an examination of some key tax cases during the Hughes Court era in the areas of corporate income, trusts, and married couples. The trust cases are perhaps some of the most interesting, though readers should delve into all the details of the excellent cases Zhang uses.

During the 1910s and 1920s, wealthy people frequently used trusts to shift income. They would create a trust, and the trust would pay the income to those in a lower bracket. In Corliss, the grantor-taxpayer created such a trust and retained significant control rights over the corpus. The income went to his wife. The grantor-taxpayer argued this violated the apportionment clause, fell outside the Sixteenth Amendment's scope, and violated due process.

The Court rejected this argument unanimously. In its opinion, the Court said that control of the property and not the formalities of title was the important analysis. Furthermore, the attribution power was not fundamentally linked to combating tax avoidance but is rather its own power that Congress can wield. Eventually, the Court would extend this logic to trusts where the grantor-taxpayer was not the sole party that could revoke the trust, and even to irrevocable trusts. The underlying idea was that formalist ownership need not control, and Congress need not tax the party with the closest relationship to income. So long as there was some relationship to the income, Congress could tax that party.

Zhang’s caselaw analysis reveals that the roots of the attribution power are in due process. The due process envisioned, though, is different from the standard procedural and substantive due process we know today. It is an older form of due process, popular at the founding and through the nineteenth century, whereby a legislature may not adjudicate retroactively. Instead, Congress must pass laws for the general welfare with prospective effect. This concept of due process worked to prohibit Congress from taking from A to give to B.

But the income tax itself through attribution does not shift any actual ownership from A to B. If A realizes some income Y, but B also bears some significant ownership relationship to Y, Congress can attribute the income, because Congress is not changing the actual ownership of the income. Both A and B have some ownership stake in income Y, Zhang observes.

The Hughes Court adopted this view for three important reasons. First, due process attacks on attribution prove too much. Such an attack on attribution would say that if A realizes income Y and B also bears some ownership rights to income Y, then you are transferring the ownership of some part of the pretax income of Y to B. But such a view would upend almost every form of income taxation, because fundamentally, there is always some redistributive effect. For example, capping the state and local income tax deduction represents a similar type of shifting of pretax income and associated tax burdens from those living in low tax states to those living in high tax states.

Second, the government never transferred the property from A to B. Rather, the government took title to whatever tax was owed on income Y and did not give it to B.

Third, none of the parties, A and B, are adverse. Indeed, in almost all of these, there is some mutual relationship between them. Due process violations of taking from A to give to B require A and B to stand in an adverse relationship.

Zhang then points out the limits of the attribution power. Based on these ideas, there are three limits. First, there has to be a rational, non-arbitrary relationship between A and B and the underlying income Y. Second, A and B must stand in a non-adverse relationship to the underlying property interest. Third, there must be proportionality between ownership interests in the underlying property and the amount of tax levied. One may not attribute 50% of the profits to someone who owns only 2% of something. These limitations mean that entities must actually realize income, otherwise there is no income to attribute. Additionally, if it is a type of income Congress does not tax, like say the appreciation of art or fine wine, attribution will not be able to reach it.

The implications of this doctrine, as Zhang points out, are wide ranging. Most importantly, it does not foreclose wealth or unrealized gains based on constitutional considerations but instead keeps it in the political democratic realm based on policy decisions and values. Attribution says that so long as a corporation realizes income, the attribution power allows some of that gain to get attributed to corporate shareholders. Attribution, the Sixteenth Amendment, and the apportionment clause of Article I also do not prohibit so-called double taxation on the same base twice. If that were the case, even as it currently stands, the corporate income tax system would be unconstitutional, because it taxes the income at the corporate level and again upon distribution. Thus, through the attribution power, wealth taxes or mark-to-market regimes can still be on the table.

This article exemplifies Zhang's strength: deep doctrinal research that pieces together often forgotten ideas with important implications. It raises some additional points for me. First, it shows how the concepts of originalism and a historical doctrinal analysis are not the cage people imagine them to be when it comes to taxation. Indeed, the attribution power and the concept of due process Zhang puts forward has a vibe of originalism. But it instead continues the long line of ideas that taxing powers were meant to be broad. So long as it was not specifically targeted in some way, which this older form of due process seeks to avoid, originalism leaning ideas should still allow a broad array of taxing powers to Congress.

Second, the piece also highlights that because there are such broad powers granted to Congress, taxation, again so long as it is at a level of generality and does not violate key notions of due process, is fundamentally a political issue. In many ways, tax serves as a compromise between our competing values and conceptions of the nation and the state. Over-constitutionalizing obscures these political dimensions and artificially elevates technical doctrine above democratic choice. Zhang's pushback on this tendency is vital.