Banks make money from deposits by putting your cash to work the moment it lands in your account: they lend it out at higher interest rates than they pay you, invest what they don’t lend in bonds and securities, earn interest by leaving excess balances at the Federal Reserve, collect a small fee every time you use your debit card, and charge account fees on top of all that. The gap between what a bank pays depositors and what it earns from deploying their money is what funds the entire operation.
The Spread Between What You Earn and What Borrowers Pay
The biggest source of profit is the difference between the interest a bank pays you and the interest it charges borrowers. As of early 2026, the national average savings account pays roughly 0.39% APY, while the average personal loan from a commercial bank carries a rate around 12%. The bank keeps the difference, minus its operating costs. Measured across all of a bank’s loans and investments, that gap is called the net interest margin.
The strategy relies on a timing mismatch. You can pull money out of a checking account any day, but the bank lends that money out for much longer stretches: a five-year car loan, a thirty-year mortgage. Interest starts accruing on those loans immediately, and because most are backed by collateral like a home or vehicle, the bank has a fallback if a borrower stops paying.
Across the industry, the net interest margin stood at 3.39% in the fourth quarter of 2025, with community banks running slightly higher at 3.77%.1FDIC.gov. FDIC Quarterly Banking Profile Fourth Quarter 2025 Most commercial banks aim for a margin between 3% and 4%. If the cost of attracting deposits climbs faster than income from loans, that margin shrinks and profitability suffers.
Interest From the Federal Reserve
Banks also earn money by simply parking cash at the Federal Reserve. Under federal law, the Fed is authorized to pay interest on balances that banks keep in their reserve accounts.2Office of the Law Revision Counsel. 12 USC 461 – Reserve Requirements As of early 2026, that rate is 3.65%.3Federal Reserve Board. Implementation Note Issued January 28, 2026 – Decisions Regarding Monetary Policy Implementation
This gives banks a risk-free way to earn income on deposits they aren’t currently lending out. When loan demand slows, or a bank wants to hold extra cash for safety, it can still generate a return by leaving that money at the Fed rather than letting it sit idle. The rate the Fed pays also sets a floor for lending rates. Banks have little reason to make a risky loan at 3% when they can earn 3.65% with zero risk at the Fed.
Investing Deposits in Bonds and Securities
When a bank has more deposits than it can profitably lend to individual borrowers, it acts as an institutional investor. It buys low-risk, interest-bearing securities that generate steady income: U.S. Treasury bonds backed by the federal government, municipal bonds issued by local governments, and mortgage-backed securities that bundle home loans into regular payments of principal and interest. These investments typically pay more than the rates the bank offers depositors, so the spread still works in the bank’s favor.
Diversifying across different types of bonds and securities also reduces the damage any single default can do to the bank’s bottom line. Income from these investments helps the bank meet the capital levels federal regulators require.4Federal Register. Regulatory Capital Rule – Revisions to the Community Bank Leverage Ratio Framework
Debit Card Interchange Fees
Every time you swipe or tap a debit card linked to your deposit account, the bank earns a small fee from the merchant’s payment processor. Card networks set these interchange fees, but federal rules cap what large banks can charge. For banks with $10 billion or more in assets, the maximum is 21 cents plus 0.05% of the transaction value, with an additional 1 cent allowed for fraud prevention.5eCFR. 12 CFR Part 235 – Debit Card Interchange Fees and Routing (Regulation II) Smaller banks are exempt from the cap and typically earn more per transaction.
On a $50 purchase at a covered bank, the interchange fee runs roughly 24 cents. Small by itself. But multiplied across millions of daily transactions, the revenue adds up quickly. This is why banks encourage you to use your debit card and may waive monthly fees if you hit a certain number of transactions per month.
Fees Charged on the Account Itself
Banks also collect a range of fees directly tied to maintaining your account. This non-interest income provides revenue that doesn’t depend on where interest rates happen to be. The most common charges include:
- Monthly maintenance fees, typically $5 to $25 if you fall below a minimum balance or don’t receive direct deposits. Many banks waive these once you meet specific thresholds.
- Overdraft fees, around $35 per occurrence at most large banks.
- Out-of-network ATM fees, several dollars per withdrawal when you use a machine not owned by your bank, sometimes charged by both your bank and the ATM operator.
- Stop-payment fees, roughly $15 to $36 when you ask the bank to block a check you’ve written from being cashed.
- Paper statement fees, a few dollars per month if you opt for mailed statements instead of electronic delivery.
These fees serve as a reliable income floor. Even in periods when low interest rates squeeze the net interest margin, fee income keeps flowing.
What Deposits Cost the Bank
Taking in deposits isn’t free. Every federally insured bank must pay premiums to the Federal Deposit Insurance Corporation to maintain the fund that protects depositors up to $250,000 per person, per bank, per ownership category.6FDIC.gov. Your Insured Deposits Premiums are based on how much insured deposits a bank holds and how risky regulators consider the bank to be.
Assessment rates for well-rated, established banks range from about 2.5 to 18 basis points per year, meaning roughly 2.5 to 18 cents for every $100 in deposits. Banks with weaker regulatory ratings or more complex operations can pay up to 42 basis points.7FDIC.gov. FDIC Assessment Rates The FDIC has set its target reserve ratio for the insurance fund at 2% of all insured deposits for 2026.8Federal Register.