This essay offers four principles of taxation by the United States government. Taken together, the principles would give rise to a no-gimmicks flat income tax. The rate of taxation would be expressed as a whole-number percentage, not to exceed 8%. The scope of taxation would be the entire income of a person or of an entity. There would not be any exception whatever to the taxation of income at the set percentage. A model constitutional amendment is presented.In the alternative, there can be a no-gimmicks flat income tax, the rate of which would be 10%. A specified portion of tax collections would be set aside, and that portion would have to be applied to reduction of the debt of the United States government. Thereby, over time, the burden of interest payments would be alleviated. Model constitutional language is suggested.For state governments, and their subdivisions and instrumentalities, the offered principle is a prohibition of borrowing to obtain public money, of lending public money, and of using public money as a guarantee. The Anti-Federalists were right to oppose the clause, in the then-proposed United States Constitution, which intended to give open-ended borrowing authority to the United States government. As to states, subdivisions, and instrumentalities, the consequences of open-ended borrowing are evident. Every state is heavily in debt, and so is every subdivision and so is every instrumentality. The way back from irresponsible borrowing, from irresponsible lending, and from irresponsible guaranteeing, is to prohibit all borrowing, all lending, and all guaranteeing. A model state constitutional amendment is presented