Banks pay interest by calculating a percentage of your account balance and depositing that amount into your account on a set schedule—usually monthly or daily, depending on the bank and account type.

The bank uses your money to make loans to other customers and invest in securities. In return, they pay you a portion of what they earn. The amount you receive depends on three things: how much money sits in your account, what interest rate the bank offers, and how often they calculate and add the interest (called the compounding frequency).

Most savings accounts compound interest daily, meaning the bank calculates what you owe each day and adds it to your balance. Some accounts compound monthly or quarterly. The more often interest compounds, the more you earn, because you start earning interest on the interest itself.

Key Takeaways

  • Banks calculate interest as a percentage of your balance and pay it on a schedule set by the account terms—usually monthly or daily.
  • The interest rate varies by bank and account type; online banks typically offer higher rates than brick-and-mortar banks.
  • Daily compounding means the bank adds interest to your balance every day, so you earn interest on interest, which increases your total earnings over time.
  • Your bank must disclose the Annual Percentage Yield (APY) before you open an account, which shows the total interest you will earn in one year including compounding.
  • Interest rates change over time and are set by each bank independently, so comparing rates across banks before opening an account can significantly increase your earnings.

How the interest rate is set and what it depends on

Banks set their own interest rates based on the Federal Funds Rate—the rate the Federal Reserve sets for banks to lend to each other. When the Fed raises rates, banks typically raise savings account rates. When the Fed lowers rates, banks lower them too. However, banks do not move at the same speed or by the same amount, so rates vary widely across institutions.

Online banks usually offer higher rates than traditional banks because they have lower overhead costs. A brick-and-mortar bank with physical branches pays for buildings, staff, and utilities; an online bank does not. That savings gets passed to customers as higher interest rates. High-yield savings accounts, offered by both online and some traditional banks, pay significantly more than standard savings accounts at the same bank.

Account type also matters. Money market accounts sometimes pay more than savings accounts. Certificates of Deposit (CDs) lock your money away for a set term—three months, one year, five years—and pay a fixed rate that is usually higher than a savings account rate for the same bank. The longer the term, the higher the rate tends to be.

Understanding Annual Percentage Yield (APY)

The Annual Percentage Yield (APY) is the total interest you will earn in one year, including the effect of compounding. It is different from the interest rate itself. For example, a bank might advertise a 4.50% interest rate with daily compounding. When you factor in daily compounding, the APY might be 4.60%. That extra 0.10% comes from earning interest on interest.

Banks are required to show you the APY before you open an account. You will find it on the account disclosure document, which the bank must provide. The APY makes it easier to compare accounts across different banks, because it shows the real return you will get, not just the stated rate.

APY changes when the bank changes its rate. If you opened an account at 4.50% APY and the bank lowers rates to 3.75%, your APY drops to 3.75% (or slightly higher with compounding). You do not have to do anything; the change happens automatically.

How compounding frequency affects your earnings

Compounding is how interest earns interest. If your account compounds daily, the bank divides your annual interest rate by 365, calculates what you owe for that day, and adds it to your balance. Tomorrow, the calculation includes today's interest. Over a year, this compounds into noticeably more money than if the bank calculated interest only once at the end of the year.

Here is a concrete example. Suppose you have $10,000 in an account with a 4.00% APY. With daily compounding, you earn roughly $408 in one year. With monthly compounding, you earn roughly $406. With annual compounding (calculated once per year), you earn exactly $400. The difference grows larger as your balance grows and as the rate increases.

Most savings accounts compound daily. Some older or lower-tier accounts compound monthly or quarterly. When comparing accounts, check the compounding frequency in the disclosure document. Daily compounding is the standard to expect.

When and how the bank deposits interest into your account

Banks deposit interest on different schedules. Some deposit monthly on the first day of the month. Others deposit on the last day of the month. Some deposit quarterly. A few deposit daily, meaning the interest shows up in your balance every single day (though you may not see a separate deposit transaction).

You will see the deposit as a credit to your account. Most banks label it as "Interest Paid" or "Interest Deposit" in your transaction history. The amount varies slightly from month to month because your balance changes throughout the month, and the number of days in the month varies.

Interest is taxable income. At the end of the year, your bank sends you a Form 1099-INT if you earned $10 or more in interest during the year. You report this on your federal tax return. Some states also tax interest income. The bank does not withhold taxes from interest payments unless you request it.

Why your interest rate can change and how often it does

Interest rates on savings accounts are variable, meaning they can change at any time. Banks change rates in response to Federal Reserve decisions, market conditions, and competition. During periods when the Fed is raising rates, banks may raise savings rates weekly or monthly. During periods when the Fed is cutting rates, banks may lower rates just as frequently.

You have no control over rate changes, and the bank does not need your permission to lower your rate. However, the bank must notify you before the change takes effect. The notification usually comes by email or mail and includes the new rate and the date it becomes effective. If you disagree with a rate cut, you can move your money to another bank, but you cannot prevent the change.

Rate increases are automatic and work in your favor. Rate decreases are also automatic but work against you. This is why comparing rates across banks periodically—even if you already have an account—can help you find better returns elsewhere.

The difference between savings accounts and other interest-bearing accounts

Savings accounts are designed for money you want to keep safe and accessible. You can withdraw funds anytime without penalty. Interest rates are lower than CDs because the bank cannot count on your money staying in the account.

Money market accounts are a hybrid. They pay higher interest than savings accounts but may require a higher minimum balance and limit the number of withdrawals per month. Some money market accounts come with a debit card or checkbook, making them more like checking accounts.

Certificates of Deposit (CDs) lock your money for a fixed term. In exchange, the bank pays a higher rate. If you withdraw before the term ends, you pay a penalty—usually a few months of interest. CDs are useful if you know you will not need the money for a specific period and want to lock in a rate.

High-yield savings accounts are savings accounts with higher interest rates, usually offered by online banks. They work the same way as regular savings accounts—you can withdraw anytime—but pay significantly more interest. The tradeoff is that you may have fewer in-person services or branch locations.

Frequently Asked Questions

Does the bank pay interest on the interest I already earned?

Yes, if your account compounds interest. The bank calculates interest on your original balance plus any interest already added to the account. This is called compound interest. The more frequently the account compounds, the more interest you earn on interest.

What happens to my interest if I withdraw money mid-month?

The interest you earn depends on your balance on the day the bank calculates it. If you withdraw money before that day, the interest calculation uses the lower balance. Some banks calculate interest daily, so withdrawals affect interest earned that same day. Others calculate monthly, so a withdrawal late in the month may not affect that month's interest.

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

No. Your principal—the money you deposited—stays the same. If interest rates drop, you simply earn less interest going forward. You do not lose the money you already have or the interest you already earned.

Why do online banks pay more interest than regular banks?

Online banks have lower costs because they do not operate physical branches. They pass those savings to customers through higher interest rates. A traditional bank with hundreds of branches must pay for buildings, staff, and utilities, which reduces the money available to pay depositors.

Is the interest I earn on a savings account taxed?

Yes. Interest income is taxable at the federal level and in most states. Your bank sends you a Form 1099-INT at the end of the year if you earned $10 or more. You report this on your tax return. The bank does not withhold taxes unless you request it.