Banks pay you interest on money you keep in savings or money market accounts, and they calculate it based on your balance, the interest rate they offer, and how often they compound it

When you deposit money into a savings account, the bank lends that money to other customers through mortgages, car loans, and credit cards. In exchange, the bank pays you a portion of what it earns—that payment is interest. The amount you receive depends on three things: how much money sits in your account, what annual percentage rate (APR) the bank advertises, and how frequently the bank adds interest to your balance.

Interest is not paid all at once. Most banks compound interest daily, weekly, or monthly, meaning they calculate what you've earned and add it back into your account on a set schedule. That new balance then earns interest in the next period, so you earn interest on your interest. This compounding is why the actual amount you receive is often slightly higher than the advertised rate suggests.

Key Takeaways

  • The interest rate a bank offers is an annual percentage, but interest compounds (gets added to your account) on a schedule—usually daily or monthly—so you earn money more frequently than once per year.
  • A higher APR and a larger account balance both increase the interest you earn, but the difference between a 0.01% rate and a 4.5% rate can be hundreds of dollars per year on the same balance.
  • Interest is taxable income, and banks report it to the IRS on a Form 1099-INT if you earn $10 or more in a calendar year.
  • Checking accounts typically earn little to no interest, while savings accounts, money market accounts, and certificates of deposit (CDs) are designed to pay interest.

How the interest rate is set and what it means

Banks set their own interest rates based on what the Federal Reserve does with its benchmark rate, called the federal funds rate. When the Fed raises its rate, banks typically raise the rates they offer on savings accounts. When the Fed lowers its rate, banks usually lower theirs. However, banks do not move in lockstep—some raise rates faster than others, and some cut rates more slowly when the Fed moves down.

The rate a bank advertises is always an annual percentage. If a bank offers 4.5% APR on a savings account, that means if you kept $1,000 in the account for a full year and earned no other interest, you would receive $45. But because interest compounds, you actually earn slightly more than that simple calculation suggests. The actual amount you receive depends on how often the bank compounds.

You will also see the term Annual Percentage Yield (APY) on savings products. APY is the real rate of return after compounding is factored in. If a bank offers 4.5% APR compounded daily, the APY might be 4.60%. The difference is small on low balances but grows as your account balance increases.

How compounding increases what you earn

Compounding means the bank adds interest to your account on a regular schedule—daily, weekly, monthly, or quarterly. Once that interest is added, your new balance is higher, and the next time interest is calculated, it is calculated on the larger amount. This creates a snowball effect where you earn interest on the interest you already received.

Here is a concrete example. Suppose you have $10,000 in a savings account earning 4.8% APR compounded monthly. In the first month, the bank calculates 4.8% ÷ 12 = 0.4% of your balance. That is $10,000 × 0.004 = $40. Your new balance is $10,040. In the second month, the bank calculates 0.4% of $10,040, which is $40.16. You earned an extra $0.16 because you earned interest on the $40 from the first month. Over a full year, daily compounding produces more interest than monthly compounding on the same balance and rate, because interest is calculated and added more often.

The longer your money sits in the account, the more compounding works in your favor. After ten years at 4.8% APR compounded monthly, that same $10,000 grows to approximately $15,700. The difference between monthly and daily compounding over that period is roughly $100—not huge, but real.

Where interest rates differ across account types

Savings accounts typically offer rates between 4% and 5.5% at online banks, though brick-and-mortar banks often offer much lower rates (sometimes under 0.1%). The trade-off is that online banks have lower overhead and pass some of that savings to customers through higher rates. Savings accounts have no maturity date—you can withdraw money whenever you want, though some banks limit you to six withdrawals per month.

Money market accounts often offer slightly higher rates than savings accounts and may come with a debit card or checkbook. They usually require a higher minimum balance to open and to earn the advertised rate. If your balance falls below the minimum, the rate drops significantly.

Certificates of Deposit (CDs) offer the highest rates because you agree to lock your money away for a set period—three months, six months, one year, or longer. If you withdraw before the term ends, you pay a penalty that eats into your interest earnings. A one-year CD might offer 5.0% to 5.5%, while a five-year CD might offer 4.5% to 5.0%. Longer terms do not always pay more; it depends on what the bank expects interest rates to do.

Checking accounts rarely earn interest. Some banks offer checking accounts with interest rates between 0.01% and 2%, but these usually require you to meet conditions like setting up direct deposit, making a certain number of debit card transactions per month, or maintaining a high minimum balance.

How to calculate interest on your own

You can estimate what you will earn using a simple formula. For interest compounded annually, multiply your balance by the interest rate as a decimal:

Interest earned = Balance × (APR ÷ 100)

If you have $5,000 at 4.5% APR, you earn approximately $5,000 × 0.045 = $225 per year. For monthly compounding, divide the annual rate by 12 and apply it each month, then add that interest back to the balance before calculating the next month. Most banks publish an APY figure that already accounts for compounding, so you can also multiply your balance by the APY to get a close estimate of what you will actually receive over one year.

Online calculators and your bank's website usually have interest calculators built in. Your bank statement also shows exactly how much interest you earned in the previous month or quarter, so you can track whether the rate you are receiving matches what was advertised.

Interest and taxes

Interest income is taxable. The IRS treats it as ordinary income, which means it is added to your other income and taxed at your regular tax rate. If you earn $10 or more in interest during a calendar year, your bank sends you a Form 1099-INT by January 31 of the following year. You report this amount on your tax return.

If you earn less than $10, the bank does not send a form, but you are still required to report the interest on your tax return if you file one. Keep your bank statements as proof of the interest you earned.

The tax impact is one reason to compare rates across banks. Moving $50,000 from a bank paying 0.05% to one paying 4.5% increases your annual interest from $25 to $2,250—a difference of $2,225 before taxes. Even after paying taxes on that extra income, you come out significantly ahead.

Why rates change and how to stay on top of yours

Interest rates on savings accounts move when the Federal Reserve changes its benchmark rate, but banks do not always pass the change to customers immediately. When rates are rising, some banks raise savings rates quickly to attract deposits. When rates are falling, banks often cut savings rates slowly because they want to keep the interest they pay out as low as possible.

This means the rate you opened your account with may not be the rate you are earning six months later. Check your bank's website or your statement quarterly to see whether your rate has changed. If your bank has cut rates significantly and you have a large balance, moving your money to a bank offering a higher rate can be worth the effort. Online banks often offer the highest rates because they compete aggressively for deposits.

If you have a CD, the rate is locked in for the term you chose. When the CD matures, the bank will offer you a new rate—which may be higher or lower than what you were earning. You have a grace period (usually seven to ten days) to decide whether to renew at the new rate or move your money elsewhere.

Frequently Asked Questions

How much interest will I earn on $1,000?

At 4.5% APR compounded monthly, you earn approximately $46 in the first year. At 0.05% APR (typical for a brick-and-mortar bank), you earn about $0.50. The difference depends entirely on the bank's rate and how often interest compounds. Use your bank's calculator or multiply your balance by the APY to estimate.

Why does my bank pay less interest than the rate they advertise?

You may be earning the advertised rate but seeing it as a lower number because you are looking at monthly or quarterly interest, not annual. If your bank advertises 4.8% APR, you earn 0.4% per month (4.8% ÷ 12). Also check whether your balance has fallen below a minimum—many banks cut the rate if it does.

Is interest paid monthly or yearly?

Interest is calculated and added to your account on a schedule set by your bank—usually daily, weekly, or monthly. You see it appear in your account on that schedule, not once per year. The annual percentage rate (APR) is just how the rate is expressed; the actual payment happens more frequently.

Can I lose money if interest rates fall?

No. Interest rates falling means banks will pay you less interest going forward, but the money you already have in the account stays there. Your balance does not shrink. If you have a CD, your rate is locked in until maturity, so falling rates do not affect you until the CD matures and you decide whether to renew.

Do I have to pay taxes on interest I earn?

Yes. Interest is taxable income. If you earn $10 or more in a calendar year, your bank sends you a Form 1099-INT, and you report it on your tax return. Even if you earn less than $10, you should report it if you file a return.