Banks pay interest on savings accounts because they use your money to make their own money

When you deposit money into a savings account, the bank does not lock that cash in a vault with your name on it. Instead, the bank lends your money to other customers — for mortgages, car loans, business loans, and credit cards. Those borrowers pay the bank interest on what they borrowed. The bank keeps some of that interest as profit and pays you a portion of it as interest on your savings. You are essentially a lender, and interest is your payment for letting the bank use your money.

The amount the bank pays you depends on how much money you have on deposit and the interest rate the bank decides to offer. The interest rate is a percentage — for example, 4.5% per year. That rate is not set by the government or by law. Each bank chooses its own rate based on how much money it needs to borrow from customers and how much it can earn by lending that money out.

Key Takeaways

  • Banks lend out the money you deposit and pay you interest as your share of what they earn from those loans.
  • The interest rate your bank offers depends on what that bank needs and what other banks are offering, not on how much money you have.
  • Banks that need deposits badly (often online banks) tend to offer higher rates than banks with many existing customers.
  • The interest you earn is taxable income, and you will receive a tax form from your bank each January if you earned more than a small amount.

How banks decide what interest rate to offer

Banks compete with each other for your deposits. If one bank offers 4.5% interest and another offers 2%, you will probably move your money to the higher rate. Banks know this, so they adjust their rates based on what competitors are offering and how much money they currently need.

Online banks often offer higher rates than brick-and-mortar banks because they have lower costs — they do not pay for physical branches or as many employees. That lower cost means they can afford to pay you more interest and still make a profit. A bank that already has plenty of deposits may lower its rate because it does not need to attract new customers. A bank that is new or growing may raise its rate to pull deposits away from competitors.

The Federal Reserve, which is the central bank of the United States, also influences rates indirectly. When the Federal Reserve raises or lowers its own interest rates, banks typically raise or lower the rates they offer to customers. This happens with a delay — sometimes weeks or months — so your bank's rate may not change when ready when the Federal Reserve moves.

What happens to the interest you earn

Interest is added to your account balance, usually monthly or daily depending on the bank. If your account earns 4.5% per year and you have $10,000 on deposit, you might earn roughly $37.50 per month (the exact amount depends on how the bank calculates it). That money becomes part of your balance, and the next month you earn interest on the interest — a process called compounding.

The interest you earn is considered income by the Internal Revenue Service (IRS), the federal tax agency. If you earn more than $10 in interest during a calendar year, your bank will send you a form called a 1099-INT in January. You must report this interest on your tax return, and you may owe federal income tax on it. Some states also tax interest income. The amount of tax you owe depends on your total income and your tax bracket.

Why some accounts pay more interest than others

Not all savings accounts at the same bank pay the same rate. A money market account — a hybrid between a savings account and a checking account — often pays higher interest than a regular savings account. A certificate of deposit (CD), where you agree to leave your money untouched for a set period (three months, one year, five years), usually pays more than either one because the bank knows it can use your money for longer without you withdrawing it.

The trade-off is access. With a CD, you cannot touch your money without paying a penalty. With a money market account, you may have limits on how many withdrawals you can make per month. A regular savings account gives you full access but typically pays the lowest rate. The longer you commit your money, or the more restrictions you accept, the more interest the bank will pay.

The difference between savings account interest and investment returns

Interest on a savings account is may provide — the bank promises to pay you that rate for as long as the rate is in effect. If your account earns 4.5%, you will earn 4.5% (barring a rate change announced by the bank). This makes savings accounts very safe but also means the returns are modest.

Investments like stocks or bonds can earn much higher returns, but they can also lose value. A stock you buy for $100 might be worth $120 next year, or it might be worth $80. A savings account will never be worth less than what you put in. This safety comes at the cost of lower earnings. For money you need to access within a few years, a savings account is the right choice. For money you will not need for ten or twenty years, other investments may make more sense, but that is a separate decision from how savings accounts work.

What happens when interest rates fall

When the Federal Reserve lowers its rates, banks lower the rates they offer to customers. Your current balance will not shrink — you will not lose money — but the interest you earn on new deposits or at your next rate adjustment will be lower. If you have a CD, the rate is locked in for the term, so a rate drop does not affect you until the CD matures and you renew it.

If you have a regular savings account with a variable rate (most do), the bank can change your rate with notice, usually 30 days. Some banks lower rates quickly when the Federal Reserve moves; others wait. If your bank's rate drops and you want a higher rate, you can move your money to a different bank. There is no penalty for closing a savings account and opening one elsewhere, though you may need to wait a few business days for the transfer to complete.

Why banks cannot pay unlimited interest

A bank cannot pay you 20% interest on savings because it would not earn enough from lending to cover that cost and still make a profit. If a bank lends money at 6% and pays you 20%, it loses money on every loan. Banks also have to keep a portion of deposits on hand (called reserves) rather than lending them out, which further limits how much they can afford to pay.

Banks also face competition from each other and from other financial institutions. If one bank tried to pay 20% interest, it would attract every depositor in the country, and the bank would not have enough lending capacity to use all that money. The market naturally settles on rates that allow banks to survive and compete while paying depositors a fair share of what they earn.

Frequently Asked Questions

Can I lose money in a savings account if interest rates drop?

No. Your balance will never shrink because of a rate drop. You will straightforward earn less interest on new deposits or when your rate adjusts. The money you already have stays in your account.

Do all banks pay the same interest rate?

No. Each bank sets its own rate. Online banks typically offer higher rates than traditional banks, and rates change frequently. You can compare current rates on bank websites or financial comparison sites.

What if my bank pays interest monthly but I withdraw money mid-month?

Most banks calculate interest daily based on your balance each day, then add it to your account monthly. If you withdraw money mid-month, you earn interest only on the balance you actually held. The exact method varies by bank, so check your account agreement.

Is the interest I earn on a savings account taxable?

Yes. Interest is income, and you must report it on your tax return. If you earn more than $10 in a year, your bank will send you a 1099-INT form. The tax you owe depends on your total income and your tax bracket.

Why would I keep money in a savings account if the interest is so low?

Savings accounts are for money you need to access within a few years and want to keep safe. The interest is a bonus, not the main purpose. For money you will not need for many years, other investments may earn more, but savings accounts are the right tool for emergency funds and short-term goals.