McDermott’s Federal Tax Controversy Practice Group focuses on representing taxpayers in tax disputes with the Internal Revenue Service (IRS) in IRS examinations and IRS administrative appeals as well as litigation in federal trial and appellate courts. In resolving such disputes, it is helpful for taxpayers (and tax practitioners) to understand how the IRS operates as an organization in addition to its chain of command. To that end, below, we set forth some basic information regarding the organization and operations of the IRS.

Many of our clients are audited by the IRS’s Large Business & International (LB&I) division. On our Resources page, we added an LB&I Resources document that details its organization, including the roles and responsibilities of an LB&I examination team.


The IRS is organized to carry out the responsibilities of the US Secretary of the Treasury under Internal Revenue Code Section 7801. The Secretary has the authority to administer and enforce the internal revenue laws and the power to create an agency to enforce said laws. The IRS was created based on this grant of authority. The IRS Commissioner administers and supervises the execution and application of the internal revenue laws.

The IRS is organized into two primary organizations—the Deputy Commissioner for Services and Enforcement (DCSE) and the Deputy Commissioner for Operations Support (DCOS).

DCSE oversees the following operating divisions:

  • Wage and Investment (W&I)
  • Small Business/Self-Employed (SB/SE)
  • Large Business and International (LB&I)
  • Tax Exempt and Government Entities (TE/GE)
  • Criminal Investigation (CI)
  • Office of Professional Responsibility (OPR)
  • Whistleblower Office
  • Return Preparer Office (RPO)
  • Online Services

DCOS oversees the following integrated support functions:

  • Information Technology (IT)
  • Chief Financial Office (CFO)
  • Facilities Management and Security Services (FMSS)
  • Human Capital Office (HCO)
  • Private, Government Liaison and Disclosure (PGLD)
  • Equity, Diversity and Inclusion (EDI)
  • Office of the Chief Risk Office (CRO)
  • Procurement
  • Research Applied Analytics and Statistics (RAAS)

Certain key functions report directly to the IRS Commissioner. Those include:

  • Chief Counsel (Counsel)
  • Communications and Liaison (C&L)
  • IRS Independent Office of Appeals (Appeals)
  • National Taxpayer Advocate

Practice Point: IRS examinations are a fact of life, especially for large corporate taxpayers. The above overview and the LB&I Resources guide provide more information on how the IRS is organized and operated. The more taxpayers and tax practitioners know, the better the odds of a smooth and efficient examination process.

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