“The laws of Congress in respect to those matters [Federal Income Taxation] do not extend into the territorial limits of the states, but have force only in the District of Columbia, and other places that are within the exclusive jurisdiction of the national government.” Caha v. United States, 152 U.S. 211, 215, 14 S. Ct. [...]

[25] Reductions in excessive assessments, as opposed to assessments which become legally unenforceable in their entirety, are governed by the abatement statute, 26 U.S.C. § 6404(a): [26] (a) The Secretary is authorized to abate the unpaid portion of the assessment of any tax or any liability in respect thereof, which – [27] (1) is excessive [...]