Kimberly A. Clausing (UCLA; Google Scholar), The Revenue Consequences of Pillar 2: Five Key Considerations, 180 Tax Notes Fed. 555 (July 24, 2023):

In this article, Clausing discusses a recent analysis by the Joint Committee on Taxation [Possible Effects of Adopting the Components of the OECD’s Pillar Two, Both Worldwide and in the United States] concerning the revenue consequences of the United States adopting pillar 2 conforming tax reforms.

Bottom Line
As the JCT notes, there are large sources of uncertainty in estimates of what will happen under different hypothetical scenarios of policy adoption. However, simple common sense tells us that the agreement is good for any country that wants to raise revenue from the corporate tax. If the rest of the world agrees to tax multinational income at some base level, that helps the revenue potential of the corporate tax because it lessens the pressures of tax competition and profit shifting. The effect of the agreement on the ability of countries to collect revenue from the corporate tax is not the policy exercise that the JCT has been asked to consider in its recent report, but it is a highly relevant policy question. (The JCT’s preliminary analysis of the baseline supports these same conclusions.)

Of course, the U.S. revenue potential of the corporate tax is highest if the United States taxes multinational income throughout the world and other countries refrain from doing so. But that outcome is not realistic. The U.S. corporate community would not support those divergent tax burdens for competitiveness reasons, and foreign governments would not be content to cede all taxing rights to the United States.

The international tax agreement solves an important global collective action problem, facilitating the collection of adequate tax revenue from highly mobile multinational corporate income. This allows governments throughout the world the space to make important revenue-raising corporate tax policy changes, and it will result in a better alignment between where economic activity occurs and where taxes are paid. In the United States, it provides policy room to raise the GILTI rate, raise the corporate rate, and reconsider other tax preferences. These corporate tax policy changes have the potential to fund important fiscal priorities, lower tax rates elsewhere in the system, and reduce deficits. Simply put, the agreement helps the United States tax multinationals — if it has the courage to do so.