The initiative was an attempt to enable the agency to better understand 401(k) compliance issues, determine how its tools were working and identify any plan sponsor compliance issues, according to , director of employee plan examinations.

Now, the agency is evaluating the responses it received. Its goal is to produce an interim report by September 2011, with a final report next year, according to the .

In addition, the IRS will conduct examinations of plan sponsors that failed to return the questionnaires, Templeman said. That "involves a revenue agent visitation to determine tax liability and involves inspection of the books and records." The agent verifies that the plan is in overall compliance. In addition, plan sponsors that have received notice of an audit no longer can file an application for the Voluntary Correction Program. The IRS also is that didn't receive the questionnaire to use it as a guide to ensure that their own plans comply with the agency's regulations.

These actions show that the letters and questionnaires are serious business. To be sure, Uncle Sam doesn't make dealing with them easy -- the paper copy of this questionnaire covered 45 pages of detailed questions. However, even assembling the volume of info required to answer them likely is less taxing than a visit from the IRS auditors.