How the IRS Selects Tax Returns for Audit: Understanding the IRS Risk Identification Process.

Overview:

Many taxpayers believe that audits are random events. In reality, the audit selection process used by the Internal Revenue Service relies heavily on statistical models, information matching systems, and risk-based analysis. The IRS receives billions of data points each year from employers, financial institutions, and other third parties. These data allow the agency to compare reported information with tax returns and identify inconsistencies.

Understanding how the IRS identifies potential audit candidates can help taxpayers recognize areas of heightened scrutiny and ensure that their returns are accurate and well-documented.

The Issue:

Each year, the IRS processes more than 160 million individual tax returns and millions of business returns. Given the scale of filings, the agency must rely on automated systems and analytical tools to determine which returns merit further review.

Most returns are accepted as filed. However, certain characteristics may cause a return to receive a higher compliance risk score. Returns with higher scores may be selected for audit or for additional review by IRS examiners.

The IRS has consistently emphasized that audit selection is driven by data analysis rather than arbitrary decision-making.

Relevant Law and IRS Guidance:

Several internal systems and procedures guide the IRS audit selection process.

Discriminant Information Function (DIF):

One of the primary tools used by the IRS is the Discriminant Information Function (DIF) scoring system. DIF is a statistical algorithm designed to identify returns that deviate from expected norms for similarly situated taxpayers.

Returns are compared against historical compliance data to determine whether reported income, deductions, or credits appear inconsistent with statistical expectations.

A higher DIF score indicates a higher probability of error or underreporting and increases the likelihood that a return will be reviewed by an IRS examiner.

The IRS describes the DIF process in the Internal Revenue Manual (IRM) 4.1 – Examination Planning and Selection.

Information Return Matching:

The IRS also relies heavily on information return matching programs. Employers, banks, and other entities submit forms such as:

• Form W-2 (wage reporting)

• Form 1099-NEC and 1099-MISC

• Form 1099-INT and 1099-DIV

• Form 1099-B (broker transactions)

• Form 1098 (mortgage interest)

These information returns are compared with the taxpayer’s reported income. When discrepancies are detected, the IRS may issue a notice such as CP2000, proposing adjustments to income.

These matching programs are among the most common sources of IRS correspondence.

Related Examinations:

The IRS may also initiate audits through related examinations. For example, if a partnership or corporation is under audit, the IRS may examine returns of partners, shareholders, or other related parties.

Similarly, audits can be triggered when a taxpayer participates in transactions involving entities already under investigation.

Document Matching and Compliance Analytics:

In recent years, the IRS has expanded its use of data analytics to identify patterns of noncompliance. These methods analyze relationships between income levels, deductions, industry norms, and prior compliance history.

The U.S. Department of the Treasury and IRS leadership have repeatedly emphasized increased reliance on data analytics as part of modern tax administration.

Practical Implications for Taxpayers:

Although audits are relatively uncommon, taxpayers should understand several areas that frequently receive attention during IRS reviews.

Income Mismatches:

Income inconsistencies between a tax return and third-party information returns remain one of the most common triggers for IRS inquiries.

Taxpayers should ensure that all Forms W-2, 1099, and other reporting documents are accurately reflected on their returns.

Unusual Deduction Patterns:

Returns reporting deductions significantly higher than statistical norms for a taxpayer’s income level may receive additional scrutiny.

Examples may include unusually large charitable deductions, business losses, or high Schedule C expenses relative to reported revenue.

Cash-Intensive Businesses:

Businesses that primarily operate in cash environments may receive closer examination due to the higher risk of underreported income.

Industries commonly associated with cash transactions often face greater scrutiny from IRS examiners.

Large Refund Claims:

Refunds that appear disproportionate to reported income may also prompt further review before payment is issued.

Insights:

In practice, many IRS examinations originate not from complex investigations but from relatively simple inconsistencies between reported information and third-party data.

Taxpayers and practitioners should therefore prioritize accurate reporting of all information returns and maintain adequate documentation supporting deductions and credits claimed on the return.

Clear documentation and consistency between financial records and tax filings remain among the most effective safeguards against audit complications.

References:

• Internal Revenue Service, Internal Revenue Manual (IRM) 4.1 – Examination Planning and Selection

• Internal Revenue Service, Publication 556 – Examination of Returns, Appeal Rights, and Claims for Refund

• Internal Revenue Code §§ 7602–7605 (Examination authority)

  
  

Written by: Sam O. Pewu, EA, CTRS

Founder & Chief Client Advocate

Syncounting

Sam O. Pewu is an Enrolled Agent and Certified Tax Resolution Specialist who focuses on federal tax representation, IRS dispute resolution, tax advisory, and strategic tax planning for individuals and businesses nationwide.