In his State of the Union Address on Tuesday night, President Barack Obama is expected to take sharp aim at wealth inequality.

He'll propose a hike in the minimum wage, extended unemployment benefits, and more funding for education and skills improvement.

He is also likely to contribute to several persistent myths about the increasing gap between the rich and everyone else.

There is no question that income inequality in America is high compared with other countries as well as with the three decades in the U.S. after World War II. And a consensus is growing among business leaders, politicians and even conservatives that more must be done to help those at the bottom better adapt to a more global, technology-driven world.

(Read more: The overreaction of the 1 percent)

But as the country wrestles with one of the most fundamental issues of our time, three key myths beg to be corrected.

MYTH 1—Inequality is rising to the highest levels ever. The most common argument used is that the top 1 percent is taking more of the national income pie than ever before. In fact, the group's share of income (including their capital gains) is lower than it was in 2007, when it hit 23.5 percent. In 2012, the most recent period measured, it was 22.46 percent.

The share of income going to the top is also less than 1 percent above where it was in 2000 (21.52 percent). The years 2000 and 2007 were good economically, but few people were complaining about inequality then because overall employment was higher.