The IRS Restructuring and Reform Act of 1998 triggered a comprehensive reorganization of the IRS, which modernized the Service and made it closer to being run like a private sector organization. As such, the IRS organization is led by the Commissioner serving as the chief official, the Chief of Staff and the Deputy Chief of Staff in the executive leadership roles below, and a number of “specialized IRS units” that serve different functions.  Staff members from each of these multiple units report to the Commissioner within the IRS Organization. Here is a list of the specialized units within the IRS Organization that report directly to the Commissioner. 
- Communications and Liaison
- Office of Compliance Analytics
- Equity, Diversity and Inclusion
- Office of Research, Analysis, and Statistics
- National Taxpayer Advocate
- Chief Counsel 
- Operations Support
- Services and Enforcement
Perhaps of most interest within the IRS organization from a tax resolution standpoint is the Services and Enforcement Unit. The Deputy Commissioner for Services and Enforcement reports to the Commissioner and oversees four operating divisions and related service and enforcement functions. The following represents a list of entities and units for which the deputy is responsible:
- Wage and Investment Division
- Large Business and International Division
- Small Business/Self-Employed Division
- Tax Exempt and Government Entities Division
- Criminal Investigation
- Return Preparer Office
- Office of Professional Responsibility
- Office of Online Services
- Whistleblower Office
Another key official within the IRS organization is the Deputy Commissioner for Operations Support, who also reports directly to the Commissioner. The deputy commissioner is responsible for overseeing integrated IRS organizational support functions and facilitating better business practices within the Service. The following list of units report directly to the deputy commissioner:
- Chief Technology Officer
- Agency-Wide Shared Services
- Human Capital Officer
- Chief Financial Officer
- Office Privacy, Governmental Liaison and Disclosure
The IRS achieves many functions through one or more specialized units, the IRS publishes tax forms, collects revenues, issues administrative rulings , publishes the Internal Revenue Bulletin, and undergoes the formal regulation process of rulemaking by publishing a Notice of Proposed Rulemaking (NPRM). The organization of the modernized IRS is separated into divisions and specialized units responsible for managing the agency as well as for protecting the public interest. It is by understanding these different units and their functions that we get a sense of how the modern IRS functions and the roles that it has. We will cover each of the separate entities and how they affect taxpayers in future posts.
 As of this post, the Commissioner is Steven T. Miller, Acting.
 On matters of tax litigation, legal interpretation of the law, and tax policy, the Chief Counsel reports also to the General Counsel of the Treasury Department.
 Administrative rulings fall under two primary categories: revenue rulings and private letter rulings. A revenue ruling is where the IRS applies the law to a factual situation; the ruling is typically relied upon as a precedent for and by all taxpayers. On the other hand, a private letter ruling is a situation in which a taxpayer may seek the advice of the IRS with respect to the proper tax treatment of a transaction; the private letter ruling binds both the IRS and the requesting taxpayer. It is not cited or relied upon as a precedent similar to the revenue ruling.