About the Data

Data Coverage

The information about the federal enforcement of the tax laws by the IRS and the Justice Department on this Web site comes from many sources. This is a guide to the major agency data sources that were used. It is organized by Web site area.

  • IRS at Work
    This area summarizes information and findings on the Web site, and the sources for these are discussed in each applicable area. Additional information, particularly about IRS responsibilities and the agency's history are drawn from a book by TRAC's co-director, David Burnham, A Law Unto Itself: Power, Politics and the IRS,  Random House [New York, 1989 (hardcover), revised 1991 (paperback)], supplemented by more recent agency and General Accounting Office reports.

  • Taxpayer Burdens and Responsibilities
    This area combines information from the IRS County Income Data developed by Statistics of Income Division, with county level population estimates and geo-based files of the United States Bureau of the Census. The geo-based Census files provided the boundaries and county designations for most of the state maps with county subdivisions used as part of the navigation interface. The IRS county income series are based upon income tax returns from the Internal Revenue Service's Individual Master File (IMF). The IRS's Individual Master File includes Form 1040, 1040A, and 1040EZ individual income tax returns filed by citizens and resident aliens with the Internal Revenue Service.

  • National Profile and Enforcement Trends Over Time
    This area combines information used on the District Enforcement layers with additional sources which trace enforcement activities over a longer time period. Sources used in the District Enforcement layers are discussed elsewhere on this page. Additional information sources are noted on each table in this layer and include: internal administrative records, electronic and hardcover publications of the Internal Revenue Service; internal records and hardcover publications of the Administrative Office of the United States Courts; discussions with IRS personnel; and published reports of the General Accounting Office.

  • District Enforcement Annual Layers
    This area combines information from the Justice Department (on criminal referrals, prosecutions, and sentencing), the Office of Personnel Management (on staffing), the Internal Revenue Service (on income reported on returns and collection matters), the General Accounting Office and the Internal Revenue Service (on odds of district tax audits), and the United States Census Bureau (on population).

    Data on civil enforcement -- tax audits -- cover tax audits carried out by IRS district offices. These are the more traditional face-to-face audits which take place at an IRS office, or at the taxpayer's place of business. These are conducted by IRS revenue agents and district tax auditors. Not included in these counts are correspondence contacts from IRS Service Centers, which since a 1994 definitional change in what IRS defines as an "audit" increasingly dominate IRS's published "audit" totals. (See IRS Audit Staff and Number of Returns Audited.) No figures are available for how these Service Center "audits" are distributed geographically within districts included under a Service Center.

    Typically audits are on a per return basis. A single return may involve more than one taxpayer (for example, taxpayer and spouse). Also, a single audit may examine more than one year's return for a single taxpayer. Each return recorded by the IRS as covered by the audit is counted in these data.

    Collection enforcement activity can be on an account basis (such as taxpayer delinquent accounts), or on a "per IRS action" basis (such as levies, liens, and seizures). It is possible for the same taxpayer account to be subject to more than one IRS action. Due in part to this difference in counting basis, some percents may be over 100 where multiple actions exceed the number of accounts on which the actions were taken.

    Data on criminal enforcement cover IRS referrals for criminal prosecution from both its Office of Criminal Investigation and its Inspection Office. IRS reports that in 1995 less than 6 percent of its criminal convictions resulted from Inspection Office investigations. As a result of the IRS Restructuring and Reform Act of 1998, inspection functions were transferred to the Inspector General for Tax Administration under the Treasury Department.

    All criminal enforcement figures are based upon number of individuals (defendants or potential defendants) involved -- rather than number of cases. A single referral or case filed in court may involve more than one individual. Each defendant involved is separately counted in these figures.

    Coverage includes all referrals recommending criminal prosecution recorded as received by federal prosecutors where the Internal Revenue Service is recorded by Justice as the lead investigative agency. IRS internal criminal enforcement database records sending fewer referrals for criminal prosecution than federal prosecutors record receiving (see Serious Inaccuracies in IRS Data). This is true even though IRS says that it includes in its counts referrals on which it does not play the lead investigative role (for example, joint agency investigations where another agency such as the FBI, DEA, ATF, Customs is the primary investigative agency).

    IRS criminal investigator, revenue agent, and revenue officer counts are based upon the number of individuals on the IRS payroll as fulltime employees at the end of each fiscal year. The category of criminal investigator covers investigators both in the IRS's Office of Criminal Investigation and its Inspection Office (but see note above concerning IRS Restructuring and Reform Act of 1998). Of the 3,797 criminal investigators on the fulltime payroll according to the Office of Personnel Management at the end of fiscal year 1995 (see table), IRS records 410 are in its Inspection Office. Note: IRS figures on its total criminal investigators on the rolls in 1995 of 3,773, are slightly under that recorded by OPM. OPM data record occupational class by agency and post-of-duty, not agency organizational division within occupational class.

    Because neither the Office of Personnel Management nor the Internal Revenue Service track whether personnel are administrators rather than field agents, it is not possible to separate out the number of enforcement personnel performing purely administrative duties. Staffing figures for the Baltimore IRS district (which includes Washington, D.C.) and the Washington, D.C. federal judicial district are likely to be particularly high because of the inclusion of administrative personnel within these personnel counts. This may also be a factor in IRS districts and federal judicial districts where IRS regional offices are located.

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