Overnment re-investment of tax revenue and the impact on Income inequality

First, explain how tax rates affects the different income groups and the effect that it has on income inequality overall. Focus on general theory and NOT in any country in particular.
Second, explain how government re-investment of tax revenue increase/decrease or what type of changes does it produce on income inequality. Again, focus in theory and description NOT on quantitative information or anything related to a particular country.
Be sure to address the relationship that exists between the two areas stated above and income inequality