Banks don't hold all the money customers deposit

When you deposit money into a bank account, the bank does not lock that cash in a vault with your name on it. Instead, banks lend out most of what you deposit to other customers as mortgages, car loans, and business loans. By law, banks must keep only a small portion of deposits on hand at any given time. The exact amount varies depending on the type of account and the bank's size, but it is typically between 3% and 10% of total deposits.

This system is called fractional reserve banking. It works because not every customer withdraws their money on the same day. A bank can safely lend out deposits because statistically, only a small percentage of customers will need cash at once. If a bank miscalculates and too many customers want their money simultaneously, the bank faces a crisis called a bank run. This is rare in modern banking because of federal insurance and regulation, but it is the reason banks must keep some cash available.

Key Takeaways

  • Banks are required by federal law to hold a minimum amount of reserves, though the exact percentage depends on the bank's size and the type of account.
  • The Federal Reserve sets reserve requirements, and banks that fall short face penalties and must correct the shortfall within a set period.
  • Banks hold reserves in two forms: physical cash in vaults and branches, and electronic balances at the Federal Reserve.
  • A bank's total reserves include both required reserves (the legal minimum) and excess reserves (money kept beyond the requirement for safety and lending flexibility).

What the Federal Reserve requires banks to keep

The Federal Reserve — the central bank of the United States — sets the reserve requirement for all banks. As of recent years, the requirement is 0% for most deposit accounts, meaning banks are not legally required to hold a specific percentage of deposits in reserve. This changed in 2020 when the Federal Reserve eliminated reserve requirements to help banks lend more during economic stress.

However, banks still hold reserves voluntarily because holding zero reserves would be extremely risky. If even a small percentage of customers wanted their money at once, a bank with no reserves would have to scramble to borrow funds or sell loans quickly, both of which are expensive. Banks also face pressure from regulators and investors to maintain healthy reserve levels as a sign of financial strength.

Before 2020, reserve requirements ranged from 3% to 10% depending on the type of account and the bank's total deposits. Some banks still operate as if these requirements exist because the practice is safer and because regulators expect it.

Where banks physically keep their reserves

Bank reserves exist in two places. The first is physical cash — actual dollar bills and coins stored in bank vaults, safes, and ATM machines across the country. A large bank might have millions of dollars in physical currency distributed across hundreds of branches. This cash is what customers withdraw when they use an ATM or ask a teller for money.

The second form is electronic reserves held at the Federal Reserve. Every bank has an account at the Federal Reserve, similar to how you have an account at your bank. Banks transfer money into and out of these accounts constantly. When one customer's check clears and money moves from one bank to another, it happens through these Federal Reserve accounts. This electronic money is just as real as physical cash — it is straightforward stored as a number in a computer rather than as bills in a vault.

Most of a bank's reserves are electronic rather than physical. A bank might keep only enough physical cash to cover a few days' worth of normal withdrawals, because storing and protecting large amounts of physical currency is expensive and unnecessary.

How much cash a bank needs depends on its size and customers

A small community bank with 5,000 customers and $50 million in deposits will hold reserves very differently from a large national bank with millions of customers and hundreds of billions in deposits. Larger banks can predict customer behavior more accurately because they have more data. A small bank might keep 8% to 10% of deposits in reserve to be safe, while a large bank might keep 3% to 5%.

The type of customer also matters. A bank with many business customers who move large sums regularly needs higher reserves than a bank with mostly individual savers. A bank in a region with seasonal employment — such as tourism or agriculture — might keep higher reserves during slow seasons and lower reserves during busy seasons.

Banks also consider the types of accounts they hold. Money in checking accounts can be withdrawn when ready, so banks keep more reserves to cover these. Money in savings accounts and certificates of deposit (CDs) is less likely to be withdrawn suddenly, so banks can keep lower reserves against these accounts.

What happens when a bank doesn't have enough reserves

If a bank's reserves fall below what regulators consider safe, the bank must take action. First, it can borrow money from other banks through the federal funds market, which is an overnight lending system between banks. This is expensive but fast. Second, it can borrow directly from the Federal Reserve's discount window, which charges interest but is available 24 hours a day. Third, it can sell loans or other assets to raise cash, though this is slow and may mean selling at a loss.

If a bank cannot raise reserves quickly enough, regulators will issue warnings and may restrict the bank's ability to make new loans or pay dividends to shareholders. In extreme cases, regulators can take over a bank or force it to merge with a stronger bank. This protects customers because the Federal Deposit Insurance Corporation (FDIC) insures deposits up to $250,000 per account, so even if a bank fails, depositors get their money back.

Why banks hold more than the legal minimum

Even though reserve requirements are now zero, most banks hold reserves well above zero. They do this for three reasons. First, holding reserves is a safety buffer — if unexpected withdrawals spike or loans go bad, the bank has cash to cover losses without borrowing. Second, regulators expect it and examine banks regularly to make sure reserves are adequate. A bank with too-low reserves will face scrutiny and may be forced to raise capital or restrict lending. Third, investors and depositors trust banks more when they know the bank has substantial reserves.

Banks also hold excess reserves because they earn interest on reserves held at the Federal Reserve. When the Federal Reserve pays interest on reserves, banks are incentivized to hold more cash rather than lend it all out. When the Federal Reserve does not pay interest on reserves, banks lend out more and hold less.

How you know your money is safe even though banks lend it out

The fact that banks lend out most deposits does not put your money at risk because of federal insurance and regulation. The FDIC insures deposits up to $250,000 per depositor per bank. If a bank fails, the FDIC pays depositors from an insurance fund. This has happened fewer than 20 times in the last 20 years, and in every case, depositors with insured amounts received their full balance.

Banks are also examined regularly by federal and state regulators who check reserve levels, loan quality, and overall financial health. If a bank is in trouble, regulators know about it long before it fails and can force corrective action. Additionally, banks must maintain a certain level of capital — money the bank's owners have invested — which acts as a cushion if loans go bad.

Frequently Asked Questions

What happens to my money if the bank fails?

The FDIC insures deposits up to $250,000 per depositor per bank account type. If your bank fails, the FDIC pays you directly from its insurance fund, usually within a few days. If you have more than $250,000 at one bank, amounts above that are not insured, so some people spread large balances across multiple banks or use account types like joint accounts, which have separate insurance limits.

Can a bank run out of cash?

A bank can run out of physical cash if too many customers withdraw money at once, but this does not mean the bank has lost the money. The bank can borrow cash from other banks or the Federal Reserve within hours. A true bank failure happens when a bank cannot raise cash and has lost money on bad loans, not straightforward because customers withdrew deposits.

Do all banks hold the same percentage of reserves?

No. Large banks typically hold lower percentages because they can predict customer behavior more accurately and have access to borrowing markets. Small banks often hold higher percentages for safety. Banks also adjust reserves based on economic conditions, customer behavior, and what the Federal Reserve is paying on reserves.

Why does the Federal Reserve pay interest on reserves?

The Federal Reserve uses interest on reserves as a tool to control how much banks lend. When it pays higher interest, banks hold more reserves and lend less, which slows the economy. When it pays lower interest, banks lend more, which speeds up the economy. This is one way the Federal Reserve manages inflation and employment.

Is my money safer in a bank or under my mattress?

Your money is safer in a bank. A bank account is insured by the FDIC up to $250,000, so you cannot lose your deposit due to bank failure. Money under a mattress can be stolen, lost in a fire, or damaged. A bank also pays interest on savings accounts, so your money grows over time.