Illinois’ So-Called ‘Flat’ Tax Is a Costly Illusion, Costing Billions

April 28, 2026 - 03:51

Illinoisans are struggling to afford the basics. The least we can do is stop subsidizing the luxuries of people who have everything they need and then some. Yet, that is exactly what the state’s current tax structure does—and it is draining billions of dollars from public coffers every year.

The state’s constitution mandates a flat income tax, meaning everyone pays the same rate regardless of income. In theory, this sounds fair. In practice, it is anything but. The so-called “flat” tax is riddled with loopholes, deductions, and exemptions that overwhelmingly benefit the wealthiest residents. While a middle-class family pays a significant percentage of their income on essentials like housing, healthcare, and groceries, the ultra-wealthy can shield vast sums through capital gains preferences, retirement account shelters, and itemized deductions for mortgage interest and property taxes on multiple homes.

This isn’t a flat system—it’s a regressive one. The result is that Illinois leaves billions of dollars on the table each year, money that could fund crumbling schools, understaffed mental health services, and roads riddled with potholes. Meanwhile, the state’s budget remains in perpetual crisis, forcing cuts to programs that help the most vulnerable.

Proponents of the current system argue that taxing the rich more would drive them out of the state. But the evidence suggests otherwise. States with progressive tax structures, like California and New York, continue to attract and retain high earners. The real threat to Illinois’ economy is not fair taxation—it is a broken system that forces working families to bear an unfair burden while the wealthy enjoy tax breaks that do nothing to stimulate local growth.

It is time to stop pretending that Illinois has a flat tax. It doesn’t. And the myth is costing us billions.