Banks earn income by charging interest on loans and paying lower interest on deposits

A bank's main business is simple: it borrows money from depositors at one interest rate and lends that same money to borrowers at a higher rate. The difference between what the bank pays you on your savings account and what it charges a homebuyer for a mortgage is the bank's profit. If a bank pays you 0.5% annual interest on your savings but charges a borrower 6% on a mortgage, the bank keeps roughly 5.5% as income—minus its own operating costs.

This spread exists because banks take on risk when they lend. A depositor's money is insured by the Federal Deposit Insurance Corporation (FDIC) up to $250,000, so the bank must pay back what you deposit. A borrower, however, might default on a loan. The interest rate charged to the borrower compensates the bank for that risk, and also covers the bank's staff, buildings, technology, and regulatory compliance.

Banks also earn money through fees, investment services, and other financial products beyond simple lending and deposit accounts. Understanding these income streams helps explain why banks offer different rates to different customers and why deposit rates sometimes stay low even when the Federal Reserve raises its benchmark interest rate.

Key Takeaways

  • Banks profit from the gap between the interest rate they pay depositors and the rate they charge borrowers.
  • Loan interest is the largest source of bank income, but fees on accounts, overdrafts, and services generate significant revenue too.
  • Banks charge higher rates to riskier borrowers and lower rates to borrowers with strong credit, which affects how much profit the bank makes on each loan.
  • The Federal Reserve's interest rate decisions directly influence how much banks can earn on loans and how much they must pay on deposits.
  • Banks also earn income by investing depositor money in securities and by charging for financial advisory and investment services.

Interest income from loans

Loan interest is the largest single source of income for most banks. When you borrow money for a mortgage, car loan, or personal loan, you pay interest on that principal over time. The bank collects that interest and keeps it as revenue. The interest rate the bank charges depends on the type of loan, the borrower's credit score, the loan term, and current market conditions.

A borrower with a credit score of 750 might receive a mortgage rate of 6%, while a borrower with a score of 620 might pay 7.5% for the same loan. The bank earns more from the riskier borrower because the risk of default is higher. Over the life of a 30-year mortgage, even a 1% difference in rate generates tens of thousands of dollars in additional interest income for the bank.

Banks also earn interest on commercial loans to businesses, lines of credit, and credit card balances. Credit card interest rates are typically much higher than mortgage rates—often 18% to 25%—because credit cards are unsecured debt with higher default risk. A bank that issues credit cards earns substantial income from cardholders who carry a balance month to month.

Deposit interest and the cost of funds

Banks must pay interest on savings accounts, money market accounts, and certificates of deposit (CDs) to attract and keep depositor money. This is a cost to the bank, not income. The rate banks pay on deposits is usually much lower than the rate they charge on loans. When the Federal Reserve raises its benchmark interest rate, banks gradually raise the rates they pay on deposits—but they often raise loan rates faster, which widens their profit margin.

During periods of low interest rates, banks pay depositors very little. A savings account might earn 0.01% while a CD earns 0.5%. During periods of higher rates, those same products might pay 4% to 5%. Banks prefer low-rate environments because the gap between what they pay and what they charge stays wide. When rates rise sharply, banks must pay more to keep deposits, which squeezes their profit margin unless they can raise loan rates just as fast.

The Federal Reserve does not set deposit rates directly—banks choose those rates based on competition and market conditions. However, the Fed's benchmark rate influences all other interest rates in the economy, so Fed decisions ripple through bank income within weeks or months.

Fees and service charges

Banks earn income from dozens of fees beyond interest. Overdraft fees occur when a customer spends more than their account balance; banks typically charge $25 to $35 per overdraft. A customer who overdrafts three times in a month generates $75 to $105 in fee income for the bank from a single account. Monthly maintenance fees on checking or savings accounts, ATM fees charged to non-customers, wire transfer fees, and stop-payment fees all add up.

Credit card issuers earn interchange fees—a percentage of every transaction charged to the merchant's bank. When you swipe a card at a store, the merchant's bank pays the card issuer (often a different bank) a fee of 1% to 3% of the purchase. The card issuer keeps part of that fee and passes part to the bank that issued your card. For a bank that issues millions of cards, interchange income is substantial.

Banks also charge fees for investment services, financial advisory, wealth management, and trust administration. A bank that manages $100 million in assets for high-net-worth clients might charge 0.5% to 1% annually—$500,000 to $1 million per year—for that service. Smaller banks may not offer these services, but large regional and national banks earn significant income this way.

Investment income and securities trading

Banks invest depositor money in government bonds, corporate bonds, mortgage-backed securities, and other financial instruments. When a bank buys a bond paying 4% annual interest, it earns that 4% as income. If the bank bought the bond at a discount—paying $95 for a $100 bond—it also earns the difference when the bond matures. Banks also trade securities and earn income from the difference between the price they paid and the price they sold for.

This income stream can be volatile. When bond prices fall—which happens when interest rates rise—banks holding bonds may face losses if they sell before maturity. During the 2023 banking crisis, several regional banks failed partly because they held long-term bonds purchased when rates were low; when rates rose, those bonds lost value, and depositor withdrawals forced the banks to sell at a loss.

Large banks also operate trading desks that buy and sell securities, currencies, and derivatives on behalf of clients and for the bank's own account. Trading income can be substantial in good years and negative in bad years, making it less predictable than interest income.

How the Federal Reserve's interest rate decisions affect bank income

The Federal Reserve sets a target range for the federal funds rate—the interest rate banks charge each other for overnight loans. This rate influences all other interest rates in the economy. When the Fed raises rates, banks can charge higher rates on new loans. When the Fed lowers rates, banks must lower loan rates to stay competitive.

Banks benefit most when rates are rising because they can raise loan rates immediately but raise deposit rates more slowly. A bank might raise its mortgage rate from 5% to 6% within days of a Fed increase, but keep savings account rates at 0.5% for weeks. During that window, the bank's profit margin widens. When rates are falling, the opposite happens: banks lower loan rates quickly to stay competitive but keep deposit rates high as long as possible, which squeezes margins.

Banks also benefit from a steep yield curve—a situation where long-term interest rates are much higher than short-term rates. Banks borrow short-term (from depositors in savings accounts) and lend long-term (30-year mortgages), so a steep curve means they earn more on loans than they pay on deposits. A flat or inverted yield curve (where short-term rates are higher than long-term rates) is bad for bank profitability.

Why different banks offer different rates

Banks compete for deposits and borrowers, so rates vary between institutions. A large national bank with billions in deposits may offer lower rates because it has stable funding and lower risk. A smaller regional bank might offer higher deposit rates to attract money it needs for lending. Online banks, which have lower overhead costs than brick-and-mortar branches, often offer higher savings rates and lower loan rates than traditional banks.

Banks also adjust rates based on their current funding needs. If a bank has excess deposits and needs more loans to put that money to work, it might lower deposit rates and lower loan rates to attract borrowers. If a bank needs more deposits, it raises deposit rates. These decisions happen constantly and explain why the best savings rate today might be offered by a different bank next month.

Credit scores, loan size, and loan term also affect the rate an individual borrower receives. A borrower shopping for a mortgage will see different rates from different banks, and sometimes different rates from the same bank depending on whether they choose a 15-year or 30-year term. Banks price each loan based on the risk they perceive in that specific borrower and loan.

Frequently Asked Questions

Why do banks pay such low interest on savings accounts?

Banks pay low rates on savings because they have many sources of funding—deposits are just one. They can borrow from other banks, issue bonds, and attract deposits from businesses and institutions. When deposit rates are low, banks prefer to lend money out at higher rates rather than pay depositors more. Competition and the Federal Reserve's interest rate decisions influence how much banks must pay, but banks will always try to keep the gap between deposit rates and loan rates as wide as possible.

Do banks lose money when interest rates fall?

Banks can lose money when rates fall if they hold long-term bonds or fixed-rate loans that pay less than their cost of funding. However, falling rates also mean banks can lower deposit rates faster than loan rates fall, which can widen their margin temporarily. The real danger comes when rates fall so far that banks cannot lower deposit rates below zero, but loan rates are already very low—at that point, the margin shrinks and banks struggle to earn income.

How much of a bank's income comes from interest versus fees?

Interest income typically accounts for 60% to 80% of a bank's total revenue, depending on the bank's size and business model. Fees and other income make up the rest. Large investment banks earn more from trading and advisory fees, while community banks rely almost entirely on interest income from loans and deposits. The mix varies, but interest income is the foundation of bank profitability for nearly all institutions.

Can a bank fail if interest rates change too quickly?

Yes. If rates rise sharply, banks holding long-term bonds purchased at lower rates face losses if they must sell before maturity. If rates fall sharply, banks holding adjustable-rate loans see income drop as borrowers refinance into lower-rate loans. Banks manage these risks through hedging and careful balance sheet management, but sudden rate changes can still cause problems, especially for smaller banks with less diversified income sources.

Why do credit card interest rates stay so high even when the Federal Reserve lowers rates?

Credit card rates are higher because credit card debt is unsecured—the bank has no collateral if the borrower defaults. Mortgage rates fall when Fed rates fall because mortgages are secured by the house. Banks also price credit card rates based on expected default rates, which don't change as quickly as the Fed's benchmark rate. Competition among card issuers does influence rates, but the risk premium built into credit card rates means they stay high relative to other borrowing costs.