If employees who make more money pay a higher percentage of their income to the government, this is known as what?

It is called progressive tax. in this case the tax rate increases as the taxable amount increases.

Answer;

-Progressive tax

Explanation;

-According to this type of tax system, the taxes assessed are based on the taxable amount, and follow an increasing schedule. High-income earners pay more than low-income earners, and the tax rate, along with tax liability, increases as an individual or entity's wealth increases.

-Therefore; higher earners pay a higher percentage of taxes and more money in taxes than do lower-income earners.