And that's not even getting into state income taxes, Medicare taxes, and Social Security taxes. Those all have different brackets and some states are more regressive than others. There are states like Texas that don't have income taxes, but they make up for it by taxing everything else through things like sales and property taxes.

Of note: sales tax is always the most regressive taxation model, and tariffs are basically sales taxes on steroids.

Yes, federal income tax. Let's also add that sales tax are far more regressive than other forms of taxation. Some places use those taxes more that are more likely to disproportionately affect the lower income population.