FAIRNESS

“I. The subjects of every state ought to contribute towards the support of the government, as nearly as possible, in proportion to their respective abilities; that is, in proportion to the revenue which they respectively enjoy under the protection of the state.”

CERTAINTY

“II. The tax which each individual is bound to pay ought to be certain, and not arbitrary. The time of payment, the manner of payment, the quantity to be paid, ought all to be clear and plain to the contributor, and to every other person.”

CONVENIENCE

“III. Every tax ought to be levied at the time, or in the manner, in which it is most likely to be convenient for the contributor to pay it.”

EFFICIENCY

“IV. Every tax ought to be so contrived as both to take out and to keep out of the pockets of the people as little as possible over and above what it brings into the public treasury of the state.”

Adam Smith, Wealth of Nations, 1776