HYGO News Key Government Agencies Explained: CIA, FBI, DHS, EPA, IRS
The federal government operates through hundreds of departments, agencies, bureaus, and commissions. Five of the most consequential and frequently referenced are the CIA, FBI, DHS, EPA, and IRS. Each has a distinct mission, legal authority, and place within the government structure. This guide explains what each does, how they differ, and how they connect.
Central Intelligence Agency (CIA)
Mission
The CIA collects, analyzes, and disseminates foreign intelligence to assist the President and senior policymakers in making national security decisions [1].
Key Facts
| Attribute | Detail |
|---|---|
| Established | 1947 (National Security Act) |
| Reports to | Director of National Intelligence |
| Jurisdiction | Foreign intelligence only |
| Law enforcement authority | None |
| Employees | Classified (outside estimates exceed 20,000) |
| Headquarters | Langley, Virginia |
What the CIA Does
- Human intelligence (HUMINT): Recruits and manages foreign sources who provide classified information
- Analysis: Produces intelligence assessments on foreign governments, terrorist organizations, weapons programs, and global trends
- Covert action: Conducts secret operations directed by the President to influence events abroad
- Counterintelligence: Protects CIA operations from foreign intelligence penetration
What the CIA Does Not Do
The National Security Act gives the CIA no police, subpoena or law enforcement powers and no internal security functions. It cannot arrest people or issue warrants, and it is not the agency that runs intelligence investigations inside the United States. Domestic intelligence is the FBI’s domain.
The distinction is critical: the CIA focuses abroad; the FBI focuses at home. The FBI itself emphasizes this distinction publicly [2].
Federal Bureau of Investigation (FBI)
Mission
The FBI is the principal federal law enforcement and domestic intelligence agency, responsible for investigating federal crimes and threats to national security within the United States.
Key Facts
| Attribute | Detail |
|---|---|
| Established | 1908 (as Bureau of Investigation) |
| Parent agency | Department of Justice |
| Jurisdiction | Federal crimes, domestic intelligence |
| Law enforcement authority | Full (arrests, warrants, subpoenas) |
| Employees | ~38,000 (April 2025) [3] |
| Headquarters | Washington, D.C. |
What the FBI Does
- Federal criminal investigations: Terrorism, cybercrime, organized crime, public corruption, civil rights violations, financial fraud, and violent crime
- Counterterrorism: Investigates domestic and international terrorism threats within the US
- Counterintelligence: Identifies and neutralizes foreign intelligence activities on US soil
- Criminal justice services: Operates the National Crime Information Center (NCIC), forensic laboratories, and the Uniform Crime Reporting program
FBI vs CIA: The Key Difference
| Dimension | FBI | CIA |
|---|---|---|
| Jurisdiction | Domestic | Foreign |
| Law enforcement | Yes | No |
| Can make arrests | Yes | No |
| Reports to | Attorney General (DOJ) | Director of National Intelligence |
| Primary method | Investigation and prosecution | Intelligence collection and analysis |
Both agencies work on counterterrorism, but through different mechanisms: the FBI investigates and prosecutes; the CIA collects intelligence abroad to prevent threats from reaching US soil.
Department of Homeland Security (DHS)
Mission
DHS protects the United States from threats through border security, immigration enforcement, cybersecurity, disaster response, and transportation security [4].
Key Facts
| Attribute | Detail |
|---|---|
| Established | 2002 (in response to 9/11 attacks) |
| Type | Cabinet-level executive department |
| Employees | ~260,000 (third-largest federal department) [4] |
| Secretary | Appointed by President, confirmed by Senate |
| Headquarters | Washington, D.C. |
DHS Component Agencies
DHS is not a single agency but a department containing many agencies, each with distinct roles:
| Agency | Function |
|---|---|
| Customs and Border Protection (CBP) | Border security, ports of entry |
| Immigration and Customs Enforcement (ICE) | Immigration enforcement, investigations |
| Transportation Security Administration (TSA) | Airport and transportation security |
| U.S. Coast Guard | Maritime security, sea rescue |
| Secret Service | Presidential protection, financial crimes |
| FEMA | Disaster preparedness and response |
| Cybersecurity and Infrastructure Security Agency (CISA) | Cybersecurity, critical infrastructure |
| U.S. Citizenship and Immigration Services (USCIS) | Legal immigration processing |
How DHS Was Created
Before 9/11, the agencies now under DHS were scattered across multiple departments. The Homeland Security Act of 2002 consolidated 22 federal agencies into a single department to improve coordination. It was the largest reorganization of the federal government since the National Security Act of 1947 created what became the Department of Defense.
DHS funding has itself become a flashpoint. From February 14 to April 30, 2026, the department went unfunded for 76 days while Congress fought over immigration enforcement; the bill that ended the lapse funded TSA, FEMA, the Coast Guard and the Secret Service but left out ICE and Border Patrol [5].
Environmental Protection Agency (EPA)
Mission
The EPA writes and enforces regulations to protect human health and the environment [6].
Key Facts
| Attribute | Detail |
|---|---|
| Established | 1970 (under Reorganization Plan No. 3, proposed by President Nixon) [7] |
| Type | Independent agency (not a cabinet department) |
| Employees | ~12,800 (early 2026, down about 24% in a year) [8] |
| Administrator | Appointed by President, confirmed by Senate |
| Headquarters | Washington, D.C. |
What the EPA Does
- Regulation: Sets and enforces standards for air quality, water quality, waste disposal, and chemical safety
- Enforcement: Investigates violations and issues fines, orders cleanup of contaminated sites
- Research: Conducts scientific research on environmental and health impacts
- Superfund: Manages the cleanup of the nation’s most contaminated hazardous waste sites
- Permitting: Issues permits for activities that affect air, water, and land quality
EPA’s Regulatory Authority
The EPA derives its authority from laws passed by Congress, including:
- Clean Air Act (major amendments 1970)
- Clean Water Act (1972)
- Safe Drinking Water Act (1974)
- Resource Conservation and Recovery Act (1976)
- Comprehensive Environmental Response, Compensation, and Liability Act (Superfund, 1980)
The EPA does not create law. It implements and enforces the environmental laws Congress passes. Congress determines environmental policy; the EPA executes it.
Internal Revenue Service (IRS)
Mission
The IRS administers the federal tax code and collects federal taxes [9].
Key Facts
| Attribute | Detail |
|---|---|
| Established | 1862 (as the office of the Commissioner of Internal Revenue) |
| Parent agency | Department of the Treasury |
| Employees | ~74,000 (end of 2025, down from ~102,000 a year earlier) [10] |
| Commissioner | Appointed by President, confirmed by Senate |
| Headquarters | Washington, D.C. |
What the IRS Does
- Tax collection: In fiscal 2025 it processed almost 162.8 million individual income tax returns and collected more than $5.3 trillion [9]
- Taxpayer services: Provides forms, guidance, and assistance for filing tax returns
- Enforcement: Audits tax returns, investigates tax fraud and evasion
- Criminal investigation: The IRS Criminal Investigation division investigates financial crimes including tax evasion, money laundering, and identity theft
- Tax-exempt organizations: Grants and monitors tax-exempt status for nonprofits, charities, and other organizations
IRS and the Federal Budget
The IRS is the collection mechanism for the revenue side of the federal budget. The tax laws it enforces are written by Congress, primarily through the House Ways and Means Committee and Senate Finance Committee, both key congressional committees.
How These Agencies Interact
Several of these agencies regularly work together:
- CIA and FBI share terrorism intelligence through the Director of National Intelligence and the National Counterterrorism Center, and the FBI leads Joint Terrorism Task Forces that include other agencies
- DHS and FBI coordinate on domestic terrorism investigations and border security intelligence
- FBI and IRS work together on financial crime cases, with IRS Criminal Investigation providing forensic accounting expertise
- EPA and the FBI or DHS can overlap when environmental crimes or attacks on water and chemical facilities are investigated
Key Takeaways
- The CIA collects foreign intelligence; the FBI handles domestic law enforcement and intelligence
- DHS consolidated 22 agencies after 9/11 to coordinate homeland security
- The EPA enforces environmental law passed by Congress; it does not create law independently
- The IRS collects federal taxes and enforces the tax code under the Treasury Department
- These agencies frequently collaborate but maintain distinct jurisdictions and authorities
Next Steps
- Understand the government structure these agencies operate within: three branches guide
- Learn how agencies are funded through our federal budget process guide
- Explore how Congress oversees agencies in our congressional committees explainer
Sources
- Central Intelligence Agency: About CIA
- FBI: Frequently Asked Questions
- Congressional Research Service: The Federal Bureau of Investigation (IF10651)
- Department of Homeland Security: About DHS
- PBS NewsHour: Trump signs Homeland Security funding bill, ending record shutdown
- EPA: Our Mission and What We Do
- EPA: The Origins of EPA
- Inside Climate News: EPA staffing hits 40-year low (March 6, 2026)
- IRS: IRS describes agency’s activities in Fiscal Year 2025 Data Book
- Associated Press via WDIV: IRS faces stiff challenges in 2026 tax season due to workforce cuts
This article is a factual reference guide to federal government agencies. It does not express political opinions or endorse any party, candidate, or policy position.