Income tax based on income

I believe it makes sense to have Progressive income taxation be based on income, so it could be set at a different rate for low, middle and upper income earners, for example, it might be 10% for low income earners, 15% for middle income and 25% for upper income. This could also be used to create, well, a regressive taxation system where low income pay 25% of their income in tax, middle income 15% and upper income 10%. Flat tax would stay the same, and not be affected.