Banks lend out the money you deposit, and keep the difference between what they pay you and what borrowers pay them

When you put money into a savings account, the bank does not lock it in a vault with your name on it. Instead, the bank uses your deposit to make loans — mortgages, car loans, business loans, credit cards. You earn interest on your balance. Borrowers pay interest on their loans. The bank keeps the spread between the two rates as profit.

This is the primary way banks fund their operations. A bank that takes in $100 million in deposits and pays depositors an average of 0.5% interest earns $500,000 a year from those accounts. If the bank lends that same $100 million out at an average rate of 6%, it brings in $6 million. The $5.5 million difference covers the bank's staff, buildings, technology, and profit.

The rates are not fixed by the bank alone. The Federal Reserve sets a benchmark rate that influences what banks pay on deposits and charge on loans. When the Fed raises rates, banks can charge borrowers more, so they can afford to pay depositors more. When the Fed cuts rates, both sides fall — but not always by the same amount, which is how banks adjust their margin.

Key Takeaways

  • Banks use your deposit to fund loans to other customers, and profit from the difference between the interest rate they pay you and the rate borrowers pay them.
  • The Federal Reserve's benchmark rate influences both savings rates and loan rates, but banks adjust their margins based on competition and their own funding needs.
  • Banks also earn money from fees — monthly maintenance, overdraft charges, wire transfer fees — though many accounts waive these if you meet balance or deposit requirements.
  • The interest rate you see advertised is the bank's choice; two banks can offer very different rates on the same type of account, depending on how aggressively they want to attract deposits.
  • When interest rates are low, banks earn less on the spread, so they may raise fees or lower deposit rates to maintain profit margins.

The interest rate spread is where most bank profit comes from

The net interest margin is the percentage difference between what a bank pays depositors and what it charges borrowers. If a bank pays 4.5% on savings and charges 7% on a personal loan, the margin is 2.5 percentage points. On a $1 million loan, that margin generates $25,000 in annual profit (before the bank's costs).

Banks do not lend out every dollar you deposit. Federal Reserve rules require banks to hold a percentage of deposits as reserve requirements — currently 0% for most account types, though this can change. Even when reserves are not legally required, banks keep cash on hand to cover withdrawals. A bank might lend out 85% to 95% of deposits and keep the rest liquid.

The margin varies by loan type and borrower risk. A mortgage to a borrower with excellent credit might carry a 6% rate, while a credit card for the same borrower might be 18%. A business loan to a startup might be 10% or higher. The bank averages these rates across its entire loan portfolio to calculate its overall margin.

Fees are the second major source of bank revenue

Beyond the interest spread, banks charge fees on accounts and transactions. A monthly maintenance fee might be $10 to $15. An overdraft fee can be $25 to $35 per occurrence. Wire transfers often cost $15 to $30. ATM fees for using another bank's machine typically run $2 to $3. A returned check or failed payment might trigger a $25 to $35 fee.

Many banks waive monthly fees if you maintain a minimum balance — often $500 to $2,500 — or set up direct deposit. Some waive overdraft fees if you link a backup account. The fee structure is a way for banks to segment customers: those who can afford to maintain high balances pay less, while those who cannot pay more.

During periods of low interest rates, fees become more important to bank profit. When the Fed keeps rates near zero, the spread between deposit rates and loan rates shrinks, so banks rely more heavily on fees to offset lost margin income. This is why overdraft and maintenance fees often rise when interest rates fall.

Competition and market conditions change what banks pay you

The rate you see on a savings account is not determined by the Fed or by law — it is set by each bank based on how much it needs deposits and what competitors are offering. During periods when banks have plenty of deposits and few borrowers, rates fall because banks do not need to attract more money. During periods when loan demand is high and deposits are scarce, rates rise.

Online banks often pay higher savings rates than brick-and-mortar banks because they have lower overhead costs. They do not maintain physical branches, so they can afford to pass more of their margin to depositors. A traditional bank might pay 0.01% on savings while an online bank pays 4.5% on the same type of account — both are profitable, but the online bank competes on rate because it has lower expenses.

When the Fed raises its benchmark rate, banks do not when ready raise deposit rates by the same amount. They wait to see if competitors move first. If deposit rates stay low while loan rates rise, the bank's margin widens and profit increases — until competitors start offering higher rates and force the bank to match them. This lag is another source of bank profit during rate-hiking cycles.

Banks also profit from investment and trading activity

Larger banks earn money by investing deposits in securities, bonds, and other financial instruments. A bank might buy Treasury bonds yielding 4% and hold them to maturity, locking in profit. Some banks trade securities actively, buying and selling to capture price movements. These activities generate revenue separate from the interest spread on loans.

This is less relevant to a consumer with a basic savings account, but it explains why large banks can afford to offer competitive rates on deposits even when the interest spread is tight. A bank earning $500 million a year from trading and investments can afford to pay depositors more because it has other revenue streams.

What happens to bank profit when interest rates fall

When the Federal Reserve cuts rates, both deposit rates and loan rates fall, but banks try to cut deposit rates faster than loan rates. A bank might drop its savings rate from 4.5% to 0.5% within weeks, but keep its mortgage rate at 6% for months. This widens the margin temporarily, but eventually loan rates fall too as borrowers refinance or shop for better deals.

To protect profit margins during low-rate environments, banks increase fees, reduce perks like free checking, or tighten requirements for fee waivers. A bank that waived overdraft fees for customers with $500 balances might raise that threshold to $2,500. These changes are how banks maintain profitability when the spread shrinks.

Depositors often see the worst of both worlds during rate cuts: savings rates fall quickly while loan rates stay high for a while. This is why shopping around for a savings account matters most when rates are falling — the bank with the highest rate today may not be the highest tomorrow, and the lag between Fed cuts and bank rate cuts creates windows where some banks offer better terms than others.

How deposit insurance affects what banks can pay

The FDIC insures deposits up to $250,000 per account holder per bank. This insurance is funded by fees banks pay to the FDIC, not by taxpayers. When a bank fails, the FDIC covers insured deposits, and the cost comes from the insurance fund, which banks replenish through premiums.

The insurance premium is a cost to the bank, and it varies based on the bank's risk profile and the health of the insurance fund. A bank with a history of risky lending pays a higher premium than a conservative bank. These premiums are factored into the bank's profit calculation and can influence how much it can afford to pay on deposits.

For a consumer, FDIC insurance means your deposits are protected up to the limit, regardless of what the bank does with your money. This protection is why banks can safely lend out your deposits — you are not at risk if a borrower defaults, because the bank absorbs that loss.

Frequently Asked Questions

Why do some banks pay much higher interest rates than others?

Online banks typically have lower operating costs because they do not maintain physical branches, so they can afford to pay more on deposits while still earning a healthy margin. Traditional banks with many branches have higher overhead and often pay less. Banks also adjust rates based on how aggressively they want to attract new deposits at any given time.

Do banks lose money if interest rates rise too fast?

Yes. If a bank locked in long-term loans at 4% and then has to pay 5% on deposits to keep customers, it loses money on the spread. Banks manage this risk by matching the maturity of their loans to the maturity of their deposits, and by using interest rate hedges. Rising rates can squeeze bank margins if they happen too quickly.

What happens to my money if the bank fails?

The FDIC insures deposits up to $250,000 per account holder per bank. If your bank fails, the FDIC pays you the full amount of your insured deposits, usually within a few business days. You do not lose money; you straightforward move your account to another bank.

Can a bank change my interest rate whenever it wants?

Yes. Savings accounts have variable rates, meaning the bank can change the rate at any time without notice. The bank is not required to give you advance warning. If you want a may provide rate, you would need a certificate of deposit (CD), which locks in a rate for a set term.

Why do banks charge overdraft fees if they are making money on my deposits?

Overdraft fees are a separate revenue stream and a way to discourage overdrafts, which create risk and administrative work for the bank. Banks also use overdraft fees to segment customers — those who overdraft frequently are less profitable, so the fee compensates for the risk and cost they create.