If voters approve Amendment 66 on Nov. 5, the average Colorado taxpayer would see a $133-a-year increase on state income taxes.

The tax hike would raise almost $1 billion for education every year, starting in 2014.

Through changes to both the state's constitution and statutes, Amendment 66 would raise the state's income tax from 4.63 percent to 5 percent.

It also would create a new tax bracket, taxing all income over $75,000 at 5.9 percent.

In Colorado, the median household income is $57,685, according to the U.S. Census Bureau quick statistics.

Assuming most Coloradans can write off about 40 percent of their income for things such as paying interest on a home mortgage, having children or donating to charity, the median taxable income in the state is about $36,000.

All of that income would be taxed in the first tier at 5 percent for an increase of around $133.

But because the tax is now graduated, higher-income earning homes would see a greater impact.

A household that brings in $200,000 a year would pay an additional $1,200, using the same assumptions as above.

Colorado Commits to Kids uses these same factors in an online tax estimator so voters can figure out how the tax would impact them at www.coloradocommits.com/calculator.

However, families or individuals that have fewer tax write-offs - they are renters, don't have kids or access to tax-sheltering health insurance plans - would see a greater impact.