We don’t normally encounter constitutional issues in federal tax. There are some, however. See e.g., Justice Ginsburg' successful constitutional attack in Moritz v. Commissioner, 469 F.2d 466 (10th Cir. 1972), cert. denied, 412 U.S. 906 (1973), memorialized in the movie On the Basis of Sex (see Sex and Tax (Federal Tax Crimes Blog 1/7/19) here, where the pre-Judge/Justice Ginsburg with her husband Marty (best tax lawyer ever) in the background succeeded in having a Code provision declared unconstitutional.
Another instance not yet successful but imagined is asserted by a minority of the Ninth Circuit in a dissent to denial of petition for rehearing en banc. Moore v. United States, 53 F.4th 507 (9th Cir. 11/22/22), CA9 here and GS here, denying the petition from Moore v. United States, 36 F.4th 930 (9th Cir. 2022), CA9 here and GS here.
While Moore is not a tax procedure case, I mention it because it illustrates the lengths to which conservative-bent judges will go to try to restrain the federal government in a way that can throw a monkey-wrench into settled expectations of our tax system. They often mount these attacks in tax procedure cases, with the APA a tool of their angst (see Bryan Camp, The APA Is Not A Hammer (Procedurally Taxing Blog 6/24/22), here. The judges on the Moore dissent were authoring Judge Bumatay (Trump) and joiners Ikuta (Bush), Callahan (Bush), and Vandyke (Trump). A frequent target for such types is the administrative state. The target this time was Congress in enacting a statute that required a type of pass-through taxation for certain foreign corporations. By pass-through, I mean requiring the owner of an entity to include in the owner’s income for tax purposes the income earned by the entity even if the income is not distributed from the entity to the shareholder. Readers of this blog who, I hope, are familiar with the tax structure we have, know that there are any number of pass-through entities that are essential to the tax we have. To mention a few, S Corporations, partnerships, and some foreign corporations. I cannot recall any serious claims by serious people that the pass-through taxation was unconstitutional.