1. Proportional taxation applies where the same tax rate is used no matter the level of income.
2. A progressive tax structure uses higher tax rates with increases in the tax base.
3. A regressive tax structure applies lower tax rates despite increases in the tax base.
The implication of the above explanations is that a progressive tax system takes a larger percentage of income from high-income groups than from low-income groups. A proportional tax system takes the same percentage of income from all income groups, while a regressive tax structure operates from the opposite angle, taking a larger percentage of income from low-income groups than from high-income groups.
Thus, one of these three tax structures may be prevalent in some countries of the world.
Learn more about the progressive, proportional, and regressive tax structures here: https://brainly.com/question/13701600