The Trump Administration faces mounting pressure from conservative thinkers and activists—including calls from its own National Economic Council director—to promulgate a U.S. Treasury Department regulation that indexes capital gains for inflation. Proponents of such a move—which is sometimes called “presidential indexation”—make three principal arguments in favor of the proposal: (1) that inflation indexing would be an economic boon; (2) that the President and his Treasury Department have legal authority to implement inflation indexing without further congressional authorization; and (3) that in any event, it is unlikely that anyone would have standing to challenge such an action in court. This Article evaluates the proponents’ three arguments and concludes that all are faulty. First, whatever the merits of comprehensive legislation that adjusts the taxation of capital gains and various other elements of the Internal Revenue Code for inflation, rifle-shot regulatory action that targets only the capital gains tax would be costly and regressive, would open a number of large loopholes that allow for rampant tax arbitrage, and would be unlikely to significantly enhance growth. Second, the legal authority for presidential indexation simply does not exist. The Justice Department under the first President Bush reached the conclusion in 1992 that the Executive Branch cannot implement inflation indexing unilaterally, and doctrinal developments in the last quarter century have—if anything—strengthened that conclusion. Third, a number of potential plaintiffs—including a Democrat-controlled House of Representatives, certain states, brokers subject to statutory basis reporting requirements, and investment funds whose tax liability could rise as a result of the regulation—would likely have standing to challenge presidential indexation in federal court. In sum, the promise of presidential indexation turns out too hollow, and calls for unilateral action should be spurned.