The duties of Congress fall into a handful of clear categories: writing federal law, controlling taxes and spending, declaring war and funding the military, overseeing the executive branch, confirming presidential appointments and approving treaties in the Senate, proposing constitutional amendments, and handling a set of specific tasks the Constitution assigns to no one else. Article I lays most of it out, with a few additional responsibilities scattered through Article II, Article IV, Article V, and the amendments.1Constitution Annotated. Article I Legislative Branch
Writing Federal Law
The central job is legislation. Article I vests “all legislative Powers herein granted” in Congress, meaning no other branch can create federal statutes.1Constitution Annotated. Article I Legislative Branch Members introduce bills, committees examine and revise them, and each chamber votes. A bill needs a majority in both the House and the Senate before it can go to the President.
If the President vetoes a bill, Congress can override the veto with a two-thirds vote in each chamber, turning it into law without a presidential signature.2Congress.gov. Veto Override Procedure in the House and Senate The threshold is high enough that overrides are rare, but the option exists so the President cannot permanently block legislation.
Much of what Congress legislates on rests on the Commerce Clause, which authorizes it to regulate commerce among the states and with foreign nations.3Constitution Annotated. Article I Section 8 Clause 3 When a subject doesn’t map cleanly onto a specific enumerated power, the Necessary and Proper Clause allows Congress to pass laws needed to carry out its other constitutional responsibilities.4Constitution Annotated. Article I Section 8 Clause 18 Between those two clauses, the legislative reach is wide.
Controlling Federal Taxes and Spending
Congress holds the federal purse. Article I, Section 8 grants the authority to “lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States.”5Constitution Annotated. Article I Section 8 Clause 1 Revenue bills must originate in the House, keeping tax policy anchored to the chamber closest to voters.6Constitution Annotated. Origination Clause and Revenue Bills Congress also has the power to borrow on the credit of the United States and to coin money and regulate its value.7Constitution Annotated. Article I Section 8
Spending is a separate lever. The Constitution forbids the executive branch from drawing anything from the Treasury unless Congress has first passed an appropriation: “No Money shall be drawn from the Treasury, but in Consequence of Appropriations made by Law.”8Constitution Annotated. Article I Section 9 Clause 7 That single sentence is what gives Congress leverage over every federal program and agency.
The Budget Cycle
The federal fiscal year runs October 1 through September 30. Under the Congressional Budget Act of 1974, the President submits a budget request in early February, committees work through it in the spring, and appropriations bills are supposed to pass by the end of June. Deadlines slip often. When October 1 arrives without approved funding, the government operates on a continuing resolution that extends prior-year levels, or it shuts down. The FY2026 shutdown that started October 1, 2025 lasted until a continuing resolution was signed on November 12, 2025, with nonessential federal employees furloughed in the interim.9Congress.gov. The 2025 (FY2026) Government Shutdown – Economic Effects
The Debt Limit
Separately, Congress periodically raises or suspends the national debt limit, which caps how much Treasury can borrow to pay bills Congress has already authorized. Raising the limit doesn’t approve new spending; it lets the government pay for obligations already in place, including Social Security benefits, military salaries, and interest on existing debt. Congress has acted 78 times to adjust the debt limit since 1960.10U.S. Department of the Treasury. Debt Limit
Declaring War and Funding the Military
Only Congress can formally declare war. Article I, Section 8, Clause 11 assigns that power to the legislature, and neighboring clauses give Congress the authority to raise armies, maintain a navy, and write the rules governing the armed forces.11Constitution Annotated. Congressional War Powers Army funding is limited to two-year appropriations, a deliberate check meant to keep any standing military tied to ongoing civilian approval.12Constitution Annotated. Overview of the Army Clause Congress also enacted the Uniform Code of Military Justice, the statute governing conduct and legal proceedings for active-duty service members.13Office of the Law Revision Counsel. 10 USC Ch 47 – Uniform Code of Military Justice
Presidents have often sent troops into combat without a formal declaration, which is why Congress passed the War Powers Resolution in 1973. The law requires the President to notify Congress in writing within 48 hours of introducing armed forces into hostilities or imminent hostilities. If Congress does not declare war or pass a specific authorization within 60 days, the President must withdraw the forces, with a possible 30-day extension when military necessity requires safe removal.14Office of the Law Revision Counsel. 50 USC Ch 33 – War Powers Resolution Presidents of both parties have questioned the statute’s constitutionality, but it remains law, and Congress invokes it regularly.
Overseeing the Executive Branch
Passing laws is only part of the work. Congress also monitors how the executive branch carries them out. Committees hold public hearings, launch investigations, and issue subpoenas for testimony or documents when agencies resist. Two nonpartisan support agencies back this work up. The Government Accountability Office audits federal programs and reports on waste, fraud, and mismanagement; GAO reported $62.7 billion in financial benefits from its oversight work in fiscal year 2025.15U.S. Government Accountability Office. U.S. Government Accountability Office The Congressional Budget Office produces nonpartisan cost estimates for proposed legislation and economic projections that inform votes.16Congressional Budget Office. Introduction to CBO
Undoing Federal Regulations
When an agency issues a new regulation, Congress has a window to strike it down under the Congressional Review Act. A member introduces a joint resolution of disapproval, both chambers pass it, and the President signs it. If enacted, the regulation is treated as though it never took effect, and the agency cannot issue a substantially similar rule unless Congress specifically authorizes one. In the Senate, these resolutions cannot be filibustered and are capped at ten hours of debate, making them one of the few fast-track tools for reining in executive rulemaking.
Impeachment
The most serious oversight tool is impeachment. The House holds the sole power to impeach federal officials, including the President, Vice President, and federal judges.17Constitution Annotated. Article I Section 2 Clause 5 Impeachment by the House functions as a formal charge of misconduct. The Senate then conducts a trial, and conviction requires a two-thirds vote of senators present. A convicted official is removed from office and can be barred from future federal office, though impeachment does not prevent separate criminal prosecution.18Congress.gov. Overview of Impeachment Clause
Confirming Appointments and Approving Treaties
The Senate carries duties the House does not share. Under Article II, Section 2, the President nominates federal judges (including Supreme Court justices), ambassadors, and cabinet members, but none takes office until confirmed by a Senate majority.19Constitution Annotated. Article II Section 2 Clause 2 Committees examine nominees through hearings, and contested nominations can stretch on for months. That gives the Senate real influence over the federal judiciary and the leadership of executive agencies.
Treaties carry a higher bar. The President negotiates them, but they take effect only if two-thirds of senators present vote to approve.20United States Senate. About Treaties Presidents sometimes use executive agreements that don’t require Senate consent, but formal treaties remain the most binding form of international commitment under U.S. law.
Other Enumerated Powers
Article I, Section 8 also assigns Congress a set of specific powers that touch millions of people directly.
- Setting uniform national rules for naturalization (how someone becomes a U.S. citizen) and bankruptcy. Every federal immigration statute and every chapter of the Bankruptcy Code traces back to this clause.21Constitution Annotated. Article I Section 8 Clause 4
- Granting patents and copyrights to “promote the Progress of Science and useful Arts” by giving inventors and authors exclusive rights for limited periods. This is the constitutional basis for the U.S. patent and copyright system.22Constitution Annotated. Article I Section 8 Clause 8
- Establishing post offices and postal roads, which remains the basis for the United States Postal Service.
- Defining and punishing piracies, felonies on the high seas, and offenses against the law of nations, giving Congress authority over federal crimes committed outside U.S. borders.23Constitution Annotated. Article I Section 8 Clause 10
Regulating Federal Elections
State legislatures set the initial rules for congressional elections, but Congress can override them. Article I, Section 4 provides that “the Congress may at any time by Law make or alter such Regulations” for the time, place, and manner of elections for senators and representatives.24Constitution Annotated. Article I Section 4 Congress has used this power to set a uniform national Election Day (the first Tuesday after the first Monday in November), require single-member congressional districts, and establish campaign finance disclosure rules.
Constitutional and Electoral Administration
Proposing Amendments
Article V lets Congress propose amendments to the Constitution when two-thirds of both chambers vote in favor.25National Archives. Constitutional Amendment Process A proposed amendment then goes to the states, and three-fourths must ratify it before it takes effect. All 27 existing amendments were proposed through Congress rather than through the alternative state-convention route.
Counting Electoral Votes
After every presidential election, Congress meets in joint session to count and certify the electoral votes. The 12th Amendment requires the President of the Senate to open the sealed certificates from each state in the presence of both chambers, and the votes are then tallied.26Constitution Annotated. Twelfth Amendment If no candidate wins a majority of electoral votes, the House chooses the President, with each state delegation casting a single vote, and the Senate selects the Vice President.
Admitting New States
Under Article IV, Section 3, only Congress can admit new states to the Union.27Constitution Annotated. Article IV Section 3 No new state can be carved out of an existing state or formed by merging parts of existing states without the consent of the affected state legislatures and Congress. This power has been used 37 times since ratification, most recently when Hawaii was admitted in 1959.
Helping Constituents
Not every duty involves passing laws. Individual members and their staffs spend significant time helping constituents deal with the federal bureaucracy. If a Social Security check stops arriving, a veteran’s disability claim stalls, or a passport application vanishes, contacting a congressional office is one of the more effective ways to get an agency to respond. Staffers make inquiries on the constituent’s behalf. They cannot guarantee a specific outcome, but agencies tend to reply faster when a member of Congress is asking.
Members also nominate candidates to the U.S. Military Academy, Naval Academy, Air Force Academy, and Merchant Marine Academy. A congressional nomination is a prerequisite for admission to four of the five service academies; the Coast Guard Academy runs its own selection process. Applicants typically apply to their House representative and both home-state senators, and each office runs its own evaluation before making selections.