The new IRS Data Book for the government's 2008 fiscal year includes lots of tax return information. For instance, the Data Book shows that almost 1.4 million individual tax returns were audited out of 137.8 million returns filed in 2007, for an audit rate of 1.0%. While 22.3% of the audits were conducted by IRS personnel, 77.7% of the audits were correspondence audits.

The audit rate for individuals whose returns showed a total positive income (TPI) between $200,000 and $1 million rose to 2.6%.

One surprise: The audit rate in fiscal year 2008 for those with a TPI above $1 million declined from 9.3% to 5.6%. The IRS attributed this, in part, to activities related to sending out economic stimulus checks.