Sovereign currency is the official money a national government issues and recognizes as legal tender for use within its borders. In the United States, that money takes the form of Federal Reserve notes and U.S. coins, backed by the full faith and credit of the federal government rather than by gold or silver. A web of federal statutes governs who prints it, what it can be used to pay, how it is protected from counterfeiting, how damaged bills get replaced, and what has to be reported when large amounts of cash change hands.
Who Issues U.S. Currency
Two parts of the federal government work together to put dollars into your wallet. The Federal Reserve, the nation’s central bank, authorizes Federal Reserve notes, which federal law designates as “obligations of the United States” that are receivable for all taxes, customs, and other public dues.1Office of the Law Revision Counsel. 12 USC 411 – Issuance to Reserve Banks; Nature of Obligation; Redemption The physical manufacturing happens inside the Treasury Department: the Bureau of Engraving and Printing produces the paper currency, and the U.S. Mint produces coins.2Bureau of Engraving & Printing. About the Bureau of Engraving and Printing
Printed bills are only part of the story. The Federal Reserve also controls the digital side of the money supply by adjusting credit balances in accounts that commercial banks hold with it. Most dollars that move through the economy move that way, not as cash.
What “Legal Tender” Actually Means
Federal law designates U.S. coins and currency, including Federal Reserve notes, as “legal tender for all debts, public charges, taxes, and dues.”3Office of the Law Revision Counsel. 31 USC 5103 – Legal Tender If you owe a debt and offer to pay it in U.S. currency, the creditor generally cannot refuse the money and then claim you failed to pay.
The common misunderstanding is that this forces every private business to take cash. It doesn’t. Legal tender status applies to settling debts that already exist. A coffee shop that posts a “cards only” sign at the register has not violated federal law, because no debt existed before you ordered. Once a debt exists, sovereign currency gives you a definitive way to discharge it. Before a debt exists, the business sets its own payment terms.
Some state and local governments have moved to require brick-and-mortar retailers to accept physical cash, with fines for noncompliance that can reach $1,500 per violation. No federal statute does the same.
How the Federal Reserve Controls the Money Supply
The Federal Reserve uses several tools to influence how much money flows through the economy, which in turn shapes borrowing costs, employment, and inflation. The most visible is the federal funds rate, the target interest rate at which banks lend to each other overnight. As of early 2026, the target range sits at 3.50 to 3.75 percent. Changes to this rate ripple outward into mortgages, car loans, credit cards, and business borrowing.
Open Market Operations
Open market operations are the main way the Fed hits its interest rate target.4Federal Reserve. Open Market Operations When the Fed buys government securities from banks, it credits those banks’ reserve accounts, injecting money into the financial system and pushing interest rates down. Selling securities does the opposite, pulling cash out of circulation and nudging rates upward.
Reserve Requirements
Reserve requirements once set the minimum percentage of deposits banks had to hold rather than lend out. That tool is currently dormant. The Federal Reserve reduced reserve requirement ratios to zero percent effective March 26, 2020, and they have remained there since.5Federal Reserve. Federal Reserve Actions to Support the Flow of Credit to Households and Businesses The shift reflected a move to an “ample reserves” framework, where open market operations and interest rate targeting carry the weight of monetary policy.6Federal Reserve Board. Reserve Requirements
Counterfeiting Laws
Federal law treats counterfeiting as a serious crime because the value of the currency depends on public trust in it. Manufacturing counterfeit currency, including forging or altering any U.S. obligation or security, carries up to 20 years in federal prison.7Office of the Law Revision Counsel. 18 USC 471 – Obligations or Securities of United States Knowingly passing, selling, or possessing counterfeit currency with intent to defraud carries the same 20-year maximum.8Office of the Law Revision Counsel. 18 USC 472 – Uttering Counterfeit Obligations or Securities Counterfeit coins fall under a separate statute with a 15-year maximum.9Office of the Law Revision Counsel. 18 USC 485 – Coins or Bars
The U.S. Secret Service holds primary jurisdiction over counterfeiting investigations. If you receive a bill you suspect is fake, limit how many people handle it and turn it over to local law enforcement or a bank. Trying to spend it after you suspect it is counterfeit can expose you to federal prosecution even if you received it innocently.
How To Spot a Counterfeit
Modern Federal Reserve notes carry several built-in security features. The paper itself is a blend of 75 percent cotton and 25 percent linen, with small red and blue fibers embedded randomly throughout.10United States Secret Service. Know Your Money Beyond the paper, genuine notes carry a watermark visible from either side when held up to light; color-shifting ink on $10, $20, $50, and $100 notes that turns the denomination numeral from copper to green when tilted; an embedded vertical security thread on every denomination except the $1 and $2, which glows a specific color under ultraviolet light; a 3-D blue security ribbon on the $100 note showing bells and “100” symbols that appear to move; and microprinting in various locations that standard printers struggle to reproduce. Checking two or three of these features is usually enough to catch a fake. The watermark and the security thread are the easiest to verify quickly.
Replacing Damaged or Mutilated Currency
The path to replacing a damaged bill depends on how bad the damage is. Currency that is merely dirty, worn, torn, or limp counts as “unfit” and can be exchanged at any commercial bank. No government paperwork is involved.11Bureau of Engraving and Printing. Mutilated Currency FAQs
Currency that has been severely damaged by fire, water, chemicals, explosives, animals, or burial counts as “mutilated” and must be examined by the Bureau of Engraving and Printing. The BEP will redeem mutilated bills at full face value when clearly more than 50 percent of the note remains along with identifiable security features. If half or less survives, the BEP can still pay full value, but only if the evidence shows to its satisfaction that the missing portions were completely destroyed.12Bureau of Engraving & Printing. Mutilated Currency Redemption
To file a claim, complete BEP Form 5283 and mail the mutilated currency to the Bureau of Engraving and Printing at 14th and C Streets SW, Room 344A, Washington, DC 20228. Claims of $500 or more must include banking information for electronic payment.13Bureau of Engraving & Printing. How to Submit a Request for Mutilated Currency Examination Processing is first-come, first-served, and turnaround can be long. The Director of the Bureau of Engraving and Printing has final authority over redemption decisions.
Reporting Large Cash Transactions
Federal law imposes reporting duties when large amounts of physical currency change hands. The rules exist to counter money laundering and tax evasion, and not knowing them is not a defense.
Currency Transaction Reports
A financial institution must file a Currency Transaction Report for any cash transaction over $10,000, whether it is a single deposit, withdrawal, exchange, or payment. Multiple transactions by or for the same person that add up to more than $10,000 in a single day trigger the same requirement.14FinCEN. Notice to Customers – A CTR Reference Guide The bank files the report; you conduct your transaction normally.
Form 8300 for Businesses
A business that receives more than $10,000 in cash from a buyer must file IRS/FinCEN Form 8300. The trigger is not limited to a single lump payment. Installment payments that together exceed $10,000 within a year of the initial payment also require a filing.15Internal Revenue Service. IRS Form 8300 Reference Guide A business that willfully fails to file can face civil penalties and criminal prosecution.
Structuring
Deliberately breaking up cash transactions into smaller amounts to stay under the $10,000 reporting threshold is a separate federal crime called structuring. Depositing $9,500 on Monday and $9,500 on Tuesday is exactly the pattern prosecutors target. The base penalty is up to five years in prison. If the structuring involves more than $100,000 over a 12-month period or happens alongside another federal crime, the maximum rises to 10 years.16Office of the Law Revision Counsel. 31 USC 5324 – Structuring Transactions to Evade Reporting Requirement Prohibited You do not have to be laundering money or hiding income. Structuring is itself the crime, even when the underlying cash is clean.
Foreign Currency and a Tax Trap
How U.S. dollars interact with other currencies depends on the exchange rate system in place. The United States uses a floating exchange rate, where supply and demand in foreign exchange markets set the dollar’s value against other currencies. Some countries instead peg their currency to the dollar or run a managed float, where the market sets the price day to day but the central bank intervenes to prevent extreme swings.
One tax rule catches Americans off guard. Under the Internal Revenue Code, gains or losses from foreign currency transactions are generally treated as ordinary income or ordinary loss, not capital gains.17Office of the Law Revision Counsel. 26 USC 988 – Treatment of Certain Foreign Currency Transactions Ordinary income is taxed at your regular rate with no preferential treatment; long-term capital gains get lower rates. Traders in forward contracts, futures, or options on foreign currencies can elect capital gain or loss treatment, but only if they identify the transaction before the close of the day they enter into it. If you hold euros in a foreign account and the exchange rate moves in your favor before you convert back to dollars, that gain is taxable as ordinary income in the year you realize it.