Fourteenth Amendment, Section 1:
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
The Supreme Court has never decided exactly what due process is required in the assessment and collection of general taxes. Although the Court has held that
notice to the owner at some stage of the proceedings, as well as an opportunity to defend, is essential for imposition of special taxes, it has also ruled that laws for assessment and collection of general taxes stand upon a different footing and are to be construed with the utmost liberality, even to the extent of acknowledging that no notice whatever is necessary. 1 Due process of law as applied to taxation does not mean judicial process; 2 neither does it require the same kind of notice as is required in a suit at law, or even in proceedings for taking private property under the power of eminent domain. 3 Due process is satisfied if a taxpayer is given an opportunity to test the validity of a tax at any time before it is final, whether before a board having a quasi-judicial character, or before a tribunal provided by the state for such purpose. 4