Banks profit by lending out the money you deposit and charging interest on those loans

When you put money in a checking or savings account, the bank does not lock it away in a vault with your name on it. Instead, the bank lends that money to other customers — for mortgages, car loans, credit cards, and business lines of credit. The bank charges those borrowers interest on the loan. The difference between the interest rate the bank pays you on your deposit and the interest rate it charges borrowers is the bank's primary source of profit.

For example, if a bank pays you 0.01% annual interest on a savings account but charges a borrower 6% on a mortgage, the bank keeps roughly 5.99% of that spread. Multiply that across thousands or millions of deposits and loans, and the spread becomes substantial revenue. This model has worked for centuries because most depositors do not withdraw all their money at once, so the bank can safely lend out a large portion of what it holds.

Key Takeaways

  • Banks earn the majority of their profit by lending your deposits to other customers at higher interest rates than they pay you.
  • The difference between what a bank pays depositors and what it charges borrowers is called the interest rate spread, and it is the bank's main income source.
  • Banks also charge fees for services like overdrafts, wire transfers, account maintenance, and ATM use, which add to their revenue.
  • Banks are required to keep a portion of deposits on hand (called reserve requirements) and cannot lend out 100% of customer money.
  • When interest rates rise, banks can widen their profit margins because they can charge borrowers more while paying depositors less.

How the interest rate spread works in practice

The interest rate spread is the gap between what a bank pays you and what it charges borrowers. Banks do not set these rates randomly — they follow the federal funds rate, which the Federal Reserve adjusts to influence the broader economy. When the Federal Reserve raises rates, banks can charge borrowers more. When rates fall, banks often lower what they pay depositors faster than they lower what they charge borrowers, protecting their spread.

A concrete example: in 2022, when the Federal Reserve began raising rates, many banks paid savings account holders 0.01% or less while charging new mortgage borrowers 6% to 7%. By 2024, some banks raised savings rates to 4% or 5%, but mortgage rates stayed around 6% to 7%. The spread narrowed, but the bank still profited on every loan. The spread varies by loan type — credit card interest rates are much higher (often 18% to 25%), so the spread on credit cards is wider than on mortgages.

Fees are the second major source of bank revenue

Beyond interest, banks charge fees for specific services and account behaviors. These fees vary by bank and account type, but common ones include overdraft fees (charged when you spend more than your balance), monthly maintenance fees, wire transfer fees, ATM fees if you use another bank's machine, and fees for stopping payment on a check. Some banks charge fees for paper statements or for falling below a minimum balance.

Overdraft fees are particularly profitable for banks because they can be triggered repeatedly — a single purchase that overdraws your account by $5 might trigger a $35 fee. If you make multiple small purchases while overdrawn, each one can incur a separate fee. Banks also earn revenue from insufficient funds fees when a check or automatic payment bounces. These fees are not interest — they are flat charges that go directly to the bank's bottom line.

Banks invest deposits and earn returns on those investments

Beyond lending to individual customers, banks invest a portion of deposits in bonds, stocks, and other securities. When those investments earn returns, the bank keeps the profit. Banks also trade currencies and commodities, and some operate investment banking divisions that advise companies on mergers and acquisitions. These activities generate revenue separate from the interest spread on loans.

However, banks also face losses when investments decline in value or when borrowers default on loans. A bank that made many risky mortgages during a housing boom might face large losses when the market crashes. This is why banks are regulated and required to maintain a certain amount of capital (money on hand) relative to the loans they make — the capital acts as a cushion against losses.

Reserve requirements limit how much banks can lend

Banks cannot lend out every dollar deposited with them. The Federal Reserve requires banks to hold a minimum percentage of deposits in reserve — money that cannot be lent out. This reserve requirement exists to ensure banks can meet withdrawal requests and to give regulators a tool to control how much money circulates in the economy. As of 2024, the reserve requirement for most banks is 0%, but banks still hold reserves voluntarily because regulators expect it and because it protects against sudden withdrawal spikes.

The reserve requirement means a bank that receives $1 million in deposits might only be able to lend out $900,000 or $950,000, depending on the requirement and the bank's own risk management. The money held in reserve earns little or no interest, so it represents a cost to the bank. This is one reason banks prefer to attract deposits with low interest rates — the lower the rate paid to depositors, the more profitable the reserve becomes.

Interest rate changes affect bank profit margins significantly

When the Federal Reserve raises interest rates, banks can charge borrowers more, but they must also pay depositors more to keep their money. The effect on bank profit depends on how quickly rates rise and how the bank manages its loan portfolio. If rates rise suddenly, a bank with many long-term fixed-rate mortgages on its books (locked in at old, lower rates) will struggle because it must pay depositors higher rates while earning lower rates on old loans.

Conversely, when rates fall, banks that made many loans at high rates before the decline can profit handsomely — they collect high interest from borrowers while paying depositors lower rates. This is why banks often lobby for higher interest rates: a steeper spread means higher profit. During periods of very low rates (like 2010 to 2021), bank profit margins compressed, and many banks relied more heavily on fees to maintain revenue.

Different bank types have different profit models

Large national banks like JPMorgan Chase and Bank of America earn profit primarily from the interest spread on massive loan portfolios, plus substantial fee revenue and investment returns. Community banks and credit unions often rely more heavily on the interest spread because they have fewer investment opportunities and lower fee structures. Online banks typically charge fewer fees and pay higher deposit rates because they have lower overhead costs (no physical branches), but they still profit from the interest spread on loans.

Credit unions, which are member-owned rather than shareholder-owned, often return profit to members in the form of higher savings rates and lower loan rates. However, they still operate on the same basic model — lending deposits at higher rates than they pay on those deposits. The difference is that credit union profit is distributed to members rather than to external shareholders.

Frequently Asked Questions

Why do banks pay such low interest rates on savings accounts?

Banks pay low rates because they profit from the spread between what they pay depositors and what they charge borrowers. The lower the rate paid on deposits, the wider the spread and the higher the bank's profit. Banks also know that most customers will not move their money for a small rate increase, so there is little competitive pressure to raise rates unless the Federal Reserve forces the issue by raising the federal funds rate.

Can I earn more interest by moving my money to a different bank?

Yes. Online banks and some credit unions often pay higher savings rates than large national banks because they have lower overhead costs and compete more aggressively for deposits. Rates change frequently, so comparing current rates across banks before opening an account makes sense. However, the difference in interest earned is usually small unless you have a large balance.

What happens to my money if the bank fails?

Deposits up to $250,000 per depositor per bank are insured by the Federal Deposit Insurance Corporation (FDIC), a government agency. If a bank fails, the FDIC pays depositors their insured balance. This insurance exists because banks lend out most of the money deposited with them, so a bank does not have all customer deposits sitting in a vault ready to return.

Do banks profit when interest rates are very low?

Banks profit less when rates are very low because the spread between what they pay and what they charge narrows. During the 2010 to 2021 period of near-zero rates, many banks shifted toward higher-fee products and investment banking to maintain profit. When rates rise, banks typically see profit margins expand because they can charge borrowers more while keeping deposit rates lower.

How do credit card companies fit into bank profit?

Many large banks own credit card divisions or issue credit cards under their brand. Credit cards are highly profitable because the interest rates are much higher than mortgage or auto loan rates — often 18% to 25% compared to 6% to 7% for mortgages. Banks also earn interchange fees (a small percentage of each transaction) from merchants when customers use the card. These fees go to the card issuer, not the merchant's bank.