Interest is money the bank pays you for letting them use your money

When you put money in a savings account, the bank takes that money and lends it to other customers — for mortgages, car loans, credit cards, and business loans. The bank keeps the difference between what it pays you and what it charges borrowers. The amount the bank pays you is called interest, and it's calculated as a percentage of your balance.

The percentage rate is what you see advertised as the APY (Annual Percentage Yield). If your account has a 4.5% APY and you keep $1,000 in it for a full year without touching it, the bank will add roughly $45 to your account. The word "roughly" matters here — the actual amount depends on how often the bank compounds your interest, which we'll explain below.

You don't have to do anything to earn this interest. It deposits automatically according to the bank's schedule. The catch is that interest rates change, and they change often. A rate that's 4.5% today might be 3.8% next month, or it might stay the same. Banks can change the rate whenever they want, especially on accounts where the rate isn't locked in.

Key Takeaways

  • Interest is money the bank pays you for keeping your money in their account, calculated as a percentage of your balance.
  • The APY (Annual Percentage Yield) tells you the yearly rate, but interest usually deposits monthly or daily, so you earn a small amount each time.
  • Compounding means the bank pays interest on your interest, so your balance grows faster the longer money sits untouched.
  • Banks can change interest rates on most savings accounts whenever they want, so a high rate today might be lower in a few months.
  • High-yield savings accounts at online banks typically offer higher rates than traditional brick-and-mortar banks because they have lower overhead costs.

How the bank calculates the interest you earn

The bank doesn't wait until the end of the year to give you all your interest at once. Instead, it breaks the annual rate into smaller pieces and deposits interest more frequently — usually monthly or daily. If your account earns 4.5% APY and the bank compounds daily, you earn roughly 0.012% each day (4.5% divided by 365 days). That tiny daily amount gets added to your account, and the next day you earn interest on that new, slightly larger balance.

This is called compounding, and it's the reason the actual amount you earn is slightly higher than a straightforward calculation would suggest. If you earned exactly 4.5% on $1,000 once a year, you'd get $45. But if the bank compounds daily, you earn a few cents more because you're earning interest on the interest that was already added. Over months and years, compounding makes a real difference.

The more often a bank compounds — daily is better than monthly, monthly is better than quarterly — the more you earn. But the difference is usually small unless you're keeping a very large balance. What matters much more is the APY itself. A 4.5% APY compounded daily beats a 3.0% APY compounded daily by a much larger margin than daily compounding beats monthly compounding.

Why some accounts pay more interest than others

Banks set their own interest rates based on what the Federal Reserve does and what other banks are offering. When the Federal Reserve raises its benchmark rate, banks have more room to raise the rates they pay on savings accounts. When the Fed cuts rates, banks usually cut what they pay you. But banks don't all move at the same speed or to the same degree.

Online banks — banks with no physical branches — typically pay higher interest rates than traditional banks. They have lower costs because they don't maintain buildings, employ tellers, or run branch networks. They pass some of those savings to customers in the form of higher APYs. A traditional bank might offer 0.01% APY while an online bank offers 4.5% APY on the same type of account. The difference is real and worth shopping for.

Some accounts have rates that are may provide for a set period, while others change whenever the bank decides. A promotional rate is a higher rate offered for a limited time — often three to six months — to attract new customers. After the promotion ends, the rate drops to the bank's standard rate, which is usually much lower. Read the fine print to see when a promotional rate expires.

Fixed-rate accounts lock in a rate for a set time

A Certificate of Deposit (CD) is a savings account where you agree to leave your money untouched for a specific period — three months, six months, one year, five years, or longer. In exchange, the bank locks in a higher interest rate for that entire period. If you keep a $5,000 CD for one year at 5.0% APY, you'll earn roughly $250, and that rate won't change no matter what happens to other interest rates.

The tradeoff is that you can't touch the money without a penalty. If you withdraw before the term ends, the bank charges a fee that's usually several months' worth of interest. A one-year CD might have a $100 penalty for early withdrawal, which means you'd lose $100 of the interest you earned. This makes CDs best for money you know you won't need for a while.

CDs are useful when interest rates are high and you want to lock in that rate before it drops. They're less useful when rates are falling, because you'll be stuck with a rate that becomes less attractive as time goes on. Some banks offer "no-penalty CDs" where you can withdraw early without a fee, but these usually pay slightly lower rates than traditional CDs.

Money market accounts combine checking and savings features

A money market account is a hybrid between a checking account and a savings account. It pays interest like a savings account, but it also comes with a debit card and checks, like a checking account. The interest rate on a money market account is usually higher than a regular savings account but lower than a CD, because you can access the money whenever you want.

Money market accounts often have a minimum balance requirement — sometimes $2,500 or $10,000 — and the interest rate may be tiered. This means the rate changes based on how much you have in the account. If you keep $10,000 or more, you might earn 4.0% APY, but if your balance drops below $10,000, the rate might fall to 2.5% APY. Check the terms carefully to understand when the rate changes.

The main advantage of a money market account is flexibility. You can earn interest while keeping your money accessible. The main disadvantage is that the interest rate can change at any time, and the minimum balance requirement means you have to keep a larger chunk of money in the account than you might want to.

What happens to your interest when rates drop

When the Federal Reserve lowers interest rates, banks lower the rates they pay on savings accounts. If you have money in a regular savings account earning 4.5% APY and rates drop, your bank will eventually lower your rate to something like 3.5% or 2.5%. You don't lose the money you've already earned — interest that's already been added to your account stays there. But the new interest you earn going forward will be at the lower rate.

This is why timing matters. If you think rates are about to drop, locking money into a CD at the current rate protects you. If you think rates are about to rise, keeping money in a flexible savings account lets you move it to a higher-paying account later. In reality, predicting rate changes is difficult, so most people focus on finding the highest rate available right now rather than trying to time the market.

Banks can also lower rates on savings accounts even if the Federal Reserve doesn't move, straightforward because they want to. If a bank is flooded with new deposits, it might lower its rates because it doesn't need to attract more customers. If a bank is struggling, it might raise rates to pull in deposits. The rate you see today is not a promise about tomorrow.

How to compare interest rates between banks

The APY is the only number you need to compare. Ignore the interest rate (sometimes called the "nominal rate") — the APY already includes compounding, so it's the true yearly return. A bank advertising "4.5% interest rate compounded daily" is showing you the nominal rate; the APY will be slightly higher, maybe 4.51%. Always compare APYs, not nominal rates.

Check the account terms to see if the rate is promotional or standard. A promotional rate is only good for a few months, so don't base your decision on it unless you plan to move the money elsewhere when the promotion ends. Look for the "standard APY" or "regular APY" to see what you'll earn after any promotion expires.

Online banking websites and financial comparison sites list current APYs from many banks, updated regularly. You can see in one place what online banks, credit unions, and traditional banks are offering. The highest-paying accounts change frequently as banks adjust their rates, so it's worth checking every few months if you're shopping for a new account or deciding whether to move money to a different bank.

Frequently Asked Questions

Does the interest I earn count as income for taxes?

Yes. Interest earned on savings accounts is taxable income. If you earn more than $10 in interest during the year, the bank will send you a 1099-INT form in January showing how much you earned. You'll report this on your tax return. The amount owed depends on your tax bracket — someone in a higher bracket pays more tax on the same interest income than someone in a lower bracket.

What's the difference between APY and APR?

APY (Annual Percentage Yield) includes compounding and shows the true yearly return on a savings account. APR (Annual Percentage Rate) does not include compounding and is used for loans and credit cards. For savings accounts, always look at the APY. For loans, the APR tells you the true cost.

Can I lose money if interest rates drop?

No. The money you've already deposited stays in your account. If rates drop, you straightforward earn less interest going forward. The only way to lose money is if you withdraw from a CD before the term ends and pay an early withdrawal penalty that exceeds the interest you've earned.

Is a high-yield savings account the same as a money market account?

No. A high-yield savings account is a regular savings account that pays a higher interest rate, usually at an online bank. A money market account is a different product that includes checking features like a debit card and checks. High-yield savings accounts are simpler; money market accounts offer more access but often have higher minimum balances.

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

This depends on the bank's policy. Some banks calculate interest based on your average daily balance throughout the month, so withdrawing early reduces the interest you earn that month. Others calculate interest based on your balance on a specific day each month. Check your account terms to see how your bank handles this.