Most companies in US avoid federal income taxes

Here are a couple of key sentences from this article:

Two-thirds of U.S. corporations paid no federal income taxes between 1998 and 2005, according to a new report from Congress.

The GAO study did not investigate why corporations weren't paying federal income taxes or corporate taxes and it did not identify any corporations by name. It said companies may escape paying such taxes due to operating losses or because of tax credits.

So are they going to go after all the companies who didn't pay? Cause you know damn well that they would be going after your ass big time if you somehow didn't pay your taxes.