Adam smith, the father of modem political economy, has laid down four principles or cannons of taxation in his famous book "Wealth of Nations". These principles are still considered to be the starting point of sound public finance. Adam Smith's celebrated cannons of taxation are:
(1) Cannon of equality or ability, (2) Cannon of certainty, (3) Cannon of convenience, and (4) Cannon of economy.
(1) Canon of equality or ability: Canon of equality, or ability is considered j to be a very important canon of taxation. By equality we do not mean that people should pay equal amount by way of taxes to the government. By equality is meant equality of sacrifice, that is people should pay taxes in proportion to their incomes. This principle points to progressive taxation. It states that the rate or percentage of taxation should increase with the increase in income and decrease with the decrease in income. In the words of Adam Smith:
"The subject of every state ought to contribute towards the support of the government as early 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".
(2) Canon of certainty: The Canon of certainty implies that there should be certainty with regard to the amount which taxpayer is called upon to pay during the financial year. If the taxpayer is definite and certain about the amount of the tax and its time of payment, he can adjust his income to his expenditure.
The state also benefits from this principle, because it will be able to know roughly in advance the total amount which it is going to obtain and the time when it will be at its disposal. If there is an element of arbitrariness in a tax, it will then encourage misuse of power and corruption Adam smith in this connection remarks:
"The tax which each individual is bound to pay ought to be certain and not arbitrary. The time...