Those of you interested in data regarding the prevalence of certain features in 401(k) plans may find of interest the Interim Report on the Section 401(k) Compliance Check Questionnaire.  This is the first report of the IRS on the extensive questionnaire that it sent to sponsors of 401(k) plans a year or so ago.  The IRS sent the questionnaire to a random sample of 1,200 401(k) plan sponsors.  Ninety-eight percent of the plan sponsors responded.  Most answers are based on the 2008 plan year so the information is a few years out of date.  Nevertheless, the report contains good statistics on age and service requirements, entry dates, plan limits, plan contributions, etc. 

The IRS intends to issue a final report that will contain more information by size of plan.  In the meantime, 401(k) wonks can mine this data for insights on the 401(k) plan market.