If most state legislatures are considering reasonable revenue increases this year, a few, like Missouri's House, have been captured by rightwing anti-tax fundamentalists . One of the pet ideas of the far right in recent years has been eliminating the income tax for both individuals and corporations and replacing it with a sales tax applied to every transaction. The rightwing call it the "fair tax" and the Missouri House became the first legislative chamber in the country to vote for a constitutional amendment, HJR 36, that would put the issue to voters in 2010.
What would be the result? The wealthy and corporations would see a big tax cut and working families would start paying massively increased sales taxes, including on items like doctors visits and prescription drugs that have never been taxed in the past. As this analysis  by the Institute on Taxation and Economic Policy (ITEP) explains,
ITEP estimates that making HJR 36 a revenue-neutral tax change would require a new state and local average sales tax rate of 12.5 percent. This includes an increase in the basic sales tax rate of 3 percent to 9.9 percent...[T]hose with an average income of $37,000, would see an average tax hike of $2,036, the equivalent of 5.5 percent of their income...[T]he wealthiest 1 percent of Missourians, with an average income of over $1 million, would enjoy an average tax cut of $22,864 under HJR 36.
A separate report  released by the Missouri Budget Project emphasizes the special harm the "fair tax" would inflict on Missourians living on fixed incomes, since it would apply sales taxes to basic services, including utilities, rent, medical care, food, prescription drugs, and child care -- most of which are things no other state makes subject to their sales tax.
So far, it seems unlikely that the Missouri Senate will join the Missouri House in sending JHR 36 to the ballot, in that case it's perhaps useful to catch the rightwing pushing their ideology in pure form. As Rep. Roman LeBlanc (D-Kansas City) said  in denouncing the bill, the "fair tax" was just part of the attack on the middle class: "And our Middle Class in this country has been under the greatest attack that we've ever seen in the history of our country.
Citizens for Tax Justice - Missouri House GOP Approves Massive Tax Increase on the Middle-Class, Tax Cuts for the Rich 
Institute on Taxation and Economic Policy - Assessing the Impact of Missouri's "Fair Tax" Proposal: Middle Income Missourians Would Be the Hardest Hit by HJR 36 
Missouri Budget Project - Consequences of HJR 36: Proposal to Dramatically Alter Missouri’s Tax Structure Would Burden Missouri Families and Economy