The usual objection to raising taxes on the wealthy or
corporations is that such taxes undermine economic growth; yet there is
remarkably little evidence to back up those claims. Studies instead have
emphasized that neither business tax cuts nor estate tax
cuts play any significant role in local economic growth.
Instead, the sad truth is that almost every state tax
system requires working families to pay a higher percentage of their
income in taxes than their wealthier citizens. In fact, as the Institute on Taxation & Economic Policy
detailed in their 2003 study, Who
Pays?: "[O]nly four states require their best-off citizens to pay
as much of their incomes in taxes as middle-income families have to
pay." As the graph below from ITEP shows, the average family
pays significantly more of their income in state taxes than the wealthy.

A report by the Center on Budget and Policy Priorities and EPI emphasizes that making state tax systems more progressive is also a way to mitigate the broader trend of growing before-tax economic inequality.
Core Policies to Make Tax Systems More Progressive include:
General
Resources to Make Tax System More Progressive
- Institute
on Taxation and Economic Policy (ITEP) - Guide to Fair State and Local
Taxes
- ITEP
- Who Pays? A Distributional Analysis of the Tax Systems in All 50
States
- Progressive
States Network, Raising
Revenue Through Fair Taxes
- Progressive
States Network - Dos
and Don'ts of Coping With State Budget Crises
- Economic
Policy Institute - Rethinking
Growth Strategies
- Center on Budget and Policy Priorities and EPI - Pulling Apart: A State-by-State Analysis of Income Trends