Payment of taxes: fixed or variable rate?

In many countries all around the world, people pay taxes depending on their earnings. That is a fair system considering that not everyone has the same resources (money, properties…we would say property here in singular). Normally, a percentage of your incomes is destinated to contribute with the to society. As much resources you have as much you pay (you pay according to your resources (note resources here would sound a bit odd, I think income or wealth would sound better).

On the other hand we can find the opposite: everyone must contribute with a fixed amount of money. This system could increase the separate separation even more between the different social layers. People with low resources would spend part of their net revenues in paying social taxes and that could lead them to serious difficulties to buy buying essential things like food or clothes. Though However, that tax could be considered as a fancy (not sue what you mean by fancy here) payment by people with more economic power and, that way, the would become reach and reacher the rich would become richer?.

Therefore, paying taxes in function (in relation to?) of people’s salary is a more fair system which may also contribute to equilibrate the population level of life (create greater equality?).