Department of the Treasury, an executive department of the United States federal government, responsible for handling the government's fiscal affairs. It was established by the Congress of the United States in September 1789 as the successor to the Treasury Department created by the Congress of the Confederation in 1781. At its head is the secretary of the treasury, who is appointed by the president of the United States with the approval of the Senate and who is a member of the Cabinet.

The Treasury Department performs four basic functions: It formulates and recommends financial, economic, and tax policies; it serves as the government’s financial agent; it manufactures currency and coins; and it carries out certain law enforcement activities. The department's business is handled by the Office of the Secretary and nine operating bureaus. The Treasury Department maintains field offices throughout the nation and in some foreign countries.

The Internal Revenue Service is the largest of the Treasury bureaus. It is responsible for collecting federal taxes and for enforcing federal taxation laws. The Bureau of Engraving and Printing produces paper currency; Treasury securities such as notes, bills, and bonds; and postage and other stamps. The United States Mint produces and distributes both domestic and foreign coins, and it controls the processing and movement of bullion. The Bureau of the Public Debt is responsible for issuing and servicing Treasury bills, notes, and bonds. This bureau’s U.S. Savings Bonds Division promotes the sale of government savings bonds. The Office of the Comptroller of the Currency provides general supervision of national banks, including periodic bank examinations to determine compliance with rules and regulations and soundness of bank operations. The Financial Management Service is responsible for the central accounting of the monetary assets and liabilities of the U.S. Treasury and for the supervision of the government’s cash management program. The Office of Thrift Supervision (formerly the Federal Home Loan Bank Board) oversees the Federal Home Loan Bank System and the nation’s insured savings and loan associations. The Alcohol and Tobacco Tax and Trade Bureau oversees regulation and taxation of those industries. Finally, the Financial Crimes Enforcement Network helps law enforcement agencies and financial institutions to prevent and detect money laundering.

During the financial crisis that began in 2008, the worst since the Great Depression, the Treasury Department assumed wide powers. Under the $700-billion bailout package approved by Congress for the nation’s banking and other financial institutions, the secretary of the treasury obtained virtually sole discretion over how to spend the money. The legislation empowered the secretary to buy any financial instrument he deemed necessary, not just the failed mortgages and mortgage securities that gave rise to the crisis. Two separate oversight boards, one consisting of legislators and the other of regulatory and administration officials, could monitor the secretary’s actions, but the secretary alone could determine the price to be paid for the financial instruments and the process for determining the price. Under the terms of the legislation, the treasury secretary could use taxpayers’ funds to bail out foreign central banks if he chose to do so. Observers noted that it was the first time the secretary of the treasury had been given so much authority.

Oversight of the secretary’s actions consisted of frequent reports to congressional committees and the congressional oversight panel, along with audits by the comptroller general, and the appointment of an inspector general. The other oversight panel consisted of the treasury secretary, the housing secretary, and the heads of the Federal Reserve, the Securities and Exchange Commission, and the Federal Home Finance Agency.