Interest is how your bank pays you to keep money there

When you put money in a savings account, the bank uses that money to lend to other customers — for mortgages, car loans, business loans, and other purposes. In exchange for letting the bank use your money, the bank pays you interest. Interest is straightforward a percentage of your balance that the bank adds to your account on a regular schedule, usually monthly or daily.

The amount of interest you earn depends on two things: how much money you have in the account, and what interest rate the bank is offering. The interest rate is expressed as a percentage per year. If your account earns 4% annual interest and you have $1,000 in the account for a full year, you would earn $40 in interest (though the actual calculation happens in smaller pieces throughout the year).

You do not have to do anything to earn this interest. Once your money is in the account, the bank automatically calculates and deposits the interest. The money stays yours, and you can withdraw it whenever you need to.

Key Takeaways

  • Banks pay you interest on savings account balances because they use your money to make loans to other customers.
  • Interest rates vary by bank and change over time, so comparing rates before opening an account can mean hundreds of dollars in difference over a year.
  • Online banks typically offer higher interest rates than brick-and-mortar banks because their operating costs are lower.
  • Interest earned in a savings account is taxable income, and your bank will report it to the IRS if the amount exceeds a certain threshold.

How interest rates differ between banks

Not all banks offer the same interest rate. A large national bank might offer 0.01% interest, while an online bank might offer 4.5% or higher on the same type of account. The difference is real money: on a $10,000 balance, 0.01% earns you $1 per year, while 4.5% earns you $450 per year.

Banks set their own rates based on what the Federal Reserve does and what other banks are offering. When the Federal Reserve raises its benchmark interest rate, banks gradually raise the rates they pay on savings accounts. When the Federal Reserve lowers rates, bank rates fall too. This means the interest rate you see today may be different in three months or six months.

Online banks and credit unions often pay higher rates than traditional banks because they have fewer physical locations and lower operating costs. They pass some of those savings to customers in the form of higher interest rates. If you are comparing accounts, always look at the current rate being offered, not what a bank offered last year.

Understanding APY versus APR

Banks use two different terms to describe interest, and it matters which one you are looking at. APY stands for Annual Percentage Yield. APR stands for Annual Percentage Rate. For savings accounts, you want to look at APY, not APR.

APY includes the effect of compounding, which means you earn interest on your interest. If your account compounds daily, the bank calculates interest each day and adds it to your balance. The next day, you earn interest on the original balance plus the interest from the day before. Over time, this compounds and grows your money faster than straightforward interest would.

APR does not include compounding, so it understates how much you will actually earn. When you are comparing savings accounts, the APY number is the one that tells you the real return you will get. Banks are required to display APY prominently, so you should see it clearly on any account information.

How often interest is added to your account

Banks do not add all your interest at the end of the year. Instead, they calculate and add interest on a schedule — usually daily, monthly, or quarterly. The more often interest is added, the more you benefit from compounding.

If your account compounds daily, the bank divides the annual interest rate by 365, calculates that tiny amount based on your balance that day, and adds it to your account. The next day, it does the same thing with your new (slightly higher) balance. By the end of the month, you have earned interest on your interest.

Most savings accounts compound daily and credit the interest monthly, meaning the calculation happens every day but the money shows up in your account once a month. Some accounts compound and credit quarterly (four times a year) or monthly. Daily compounding is better for you because your money grows slightly faster, but the difference is usually small unless you have a very large balance.

What happens to interest when rates change

Interest rates on savings accounts are not locked in. When the Federal Reserve changes its benchmark rate, banks adjust the rates they pay on savings accounts — sometimes within days, sometimes over weeks. This means the 4.5% you see today might become 4.25% next month, or it might stay the same.

You do not lose the interest you have already earned. If you earned $100 in interest at 4.5% and the rate drops to 4.25%, that $100 is yours to keep. Going forward, you will earn interest at the new, lower rate. Your money is not at risk, and you can move it to a different bank if another bank offers a better rate.

Rising rates are good news for savers because you earn more on your balance. Falling rates are bad news because you earn less. This is one reason to pay attention to where you keep your savings — if your current bank's rate falls significantly below what other banks are offering, moving your money takes just a few days and can save you real money over time.

Taxes on interest income

Interest you earn in a savings account is taxable income. This means you owe federal income tax on it, and possibly state income tax depending on where you live. Your bank will track how much interest you earned during the year and send you a form called a 1099-INT if the amount is $10 or more.

You report this interest income on your tax return, just like you would report wages from a job. The tax you owe depends on your overall income and tax bracket. If you earned $200 in interest and you are in the 22% tax bracket, you would owe about $44 in federal income tax on that interest (though the actual calculation is more complex and depends on your total income).

This does not mean you should avoid savings accounts. It means you should factor in taxes when comparing accounts. An account earning 4.5% interest is still better than one earning 0.5%, even after taxes. The interest is still yours, and the tax is only on the earnings, not on your original deposit.

Money market accounts and CDs as alternatives

A regular savings account is not the only way to earn interest on money you are not spending right now. Money market accounts often pay slightly higher interest rates than savings accounts, though they usually require a larger minimum balance and limit how many withdrawals you can make per month.

Certificates of Deposit (CDs) pay higher interest rates than savings accounts, but in exchange you agree to leave your money in the account for a set period — three months, six months, one year, or longer. If you withdraw the money before that period ends, you pay a penalty. CDs are useful if you know you will not need the money for a specific amount of time.

For most people new to savings, a regular high-yield savings account is the best starting point. It pays more interest than a traditional bank savings account, has no withdrawal limits, and lets you access your money whenever you need it. Once you have built up savings and understand how interest works, you can explore whether a money market account or CD makes sense for your situation.

Frequently Asked Questions

How much money do I need to start earning interest?

Most banks pay interest on any balance, even $1. However, some banks require a minimum balance to open the account or to earn the advertised interest rate. Check the account details before opening — many online banks have no minimum balance requirement.

Can I lose money in a savings account?

No. Your deposit is protected by the FDIC (Federal Deposit Insurance Corporation) up to $250,000 per account. You cannot lose your original money, though the interest rate you earn can go down if the bank lowers its rate.

Is it better to keep money in a savings account or under my mattress?

A savings account is better because you earn interest on your money and it is protected by FDIC insurance. Money under a mattress earns nothing and is at risk if your home is damaged or robbed. Even a low interest rate is better than zero.

How long does it take to see interest in my account?

Interest is usually calculated daily and added to your account monthly. You should see the deposit within a few days of the end of the month. Some accounts add interest more frequently, so check your account details.

What if I withdraw money before the month ends?

You still earn interest on the balance you had during that time. If you had $1,000 for 20 days and then withdrew $500, you earn interest on the $1,000 for those 20 days, then interest on the remaining $500 for the rest of the month.