Canons of taxation  are sets of  criteria  by which to judge taxes.  These canons are still widely accepted as providing a good basis by which to judge taxes.  Adam Smith  laid down  four canons of taxation.  They are:
- Canon of Ability:  According to this principle of taxation, the people in a country should contribute towards the government expenditure. Their contribution should be according to the ability to pay of each individual. A rich man should contribute more and the poor either should contribute less  or can be exempted. This principle of taxation will ensure that the cost of public expenditure is shared by the people in accordance with their individual ability.