Interest is money the bank pays you for letting them use your money
When you put money in a savings account, the bank doesn't lock it in a vault with your name on it. Instead, the bank lends that money to other customers — for mortgages, car loans, business loans, and other purposes. The bank charges those borrowers interest (a percentage fee for using the money). The bank then shares a portion of that interest with you, as payment for letting them use your deposit.
This is how savings accounts earn interest. You don't have to do anything after you open the account. The bank calculates the interest owed to you, and deposits it into your account automatically, usually monthly or quarterly. Over time, your balance grows without you adding more money.
The amount of interest you earn depends on two main things: how much money you have in the account, and the interest rate the bank is offering. A higher rate means more money paid to you. A larger balance means more interest is calculated on that larger amount.
Key Takeaways
- Banks pay you interest because they lend out the money you deposit to other customers and keep some of the profit.
- Interest is calculated as a percentage of your balance and is added to your account automatically, usually once a month.
- The interest rate varies by bank and changes over time based on what the Federal Reserve does with national interest rates.
- Compound interest means you earn interest on your interest, so your balance grows faster the longer money sits in the account.
- Different account types (regular savings, money market, certificates of deposit) offer different interest rates, usually higher rates for accounts with restrictions.
How the interest rate is set and why it changes
Each bank decides its own interest rate for savings accounts. Banks compete with each other, so they raise or lower their rates to attract customers or reduce costs. When many banks offer low rates, it usually means the Federal Reserve — the central banking system that oversees U.S. banks — has set its own rates low. When the Federal Reserve raises its rates, banks typically raise savings account rates too, though not always by the same amount.
The rate you see advertised today may not be the rate you earn next month. Banks can change savings account rates whenever they want, with no notice required. This is different from a fixed-rate loan, where your rate is locked in. If rates drop, your earnings drop. If rates rise, your earnings rise.
Right now, savings account rates vary widely. Some banks offer less than 0.01 percent annual interest, while others offer 4 percent or higher. The difference between these rates is enormous over time. On a $10,000 balance, a 0.01 percent rate earns about $1 per year, while a 4 percent rate earns about $400 per year.
Understanding APY — the real number that matters
APY stands for Annual Percentage Yield. It is the total amount of interest you will earn in one year, including the effect of compound interest. Banks are required by law to display the APY clearly, so you can compare accounts fairly.
APY is more useful than the basic interest rate because it accounts for how often interest is added to your account. Some banks add interest monthly, some quarterly, some daily. When interest is added more often, you earn interest on your interest sooner, which means your balance grows slightly faster. APY captures this difference in one number.
When you are comparing savings accounts at different banks, always compare the APY, not the interest rate. Two banks might advertise similar rates, but if one compounds interest daily and the other compounds it quarterly, the APY will be slightly different. The difference is small on small balances, but it adds up on larger amounts or over many years.
Compound interest — earning interest on your interest
Compound interest is the reason your savings account balance grows faster over time, even if you never add more money. Here is how it works: the bank calculates interest on your balance and adds it to your account. The next time interest is calculated, it is calculated on the new, larger balance — which includes the interest from last time. You are now earning interest on your interest.
This effect is small at first but becomes noticeable over months and years. A $5,000 balance earning 4 percent APY will grow to about $5,200 after one year. After five years, it will grow to about $6,083, even though you never added another dollar. The extra $83 beyond the straightforward $1,000 in interest came from compound interest.
The longer your money stays in the account, the more compound interest works in your favor. This is why starting a savings account early, even with a small balance, can make a real difference over time.
Why some accounts earn more interest than others
Not all savings accounts offer the same interest rate. Banks offer higher rates on accounts with restrictions or requirements, because those restrictions benefit the bank.
High-yield savings accounts offer much higher rates than regular savings accounts — sometimes 4 to 5 percent compared to 0.01 percent. These accounts usually have no monthly fees and no minimum balance requirement, but they are typically offered by online banks rather than brick-and-mortar banks. Online banks have lower overhead costs, so they can afford to pay more interest.
Money market accounts offer rates between regular savings and high-yield savings. They often require a higher minimum balance and may limit how many withdrawals you can make per month. The higher rate compensates you for keeping more money in the account and accessing it less often.
Certificates of Deposit (CDs) offer the highest rates because you agree to leave your money untouched for a set period — three months, one year, five years, or longer. If you withdraw before the term ends, you pay a penalty. The bank knows your money will stay put, so it pays you more interest.
What happens to interest when you withdraw money
Interest is calculated on your balance at the time the calculation happens. If you have $5,000 in your account on the day interest is calculated, you earn interest on $5,000. If you withdraw $2,000 the next day, you do not lose the interest you already earned — it stays in your account. But going forward, interest will be calculated on the remaining $3,000.
Some banks calculate interest daily, which means your balance changes slightly every day as interest is added. Other banks calculate monthly or quarterly. The more frequently interest is calculated, the more you earn, because your balance is slightly higher each time.
If you withdraw money and then deposit it again, the interest you earn depends on when you make those moves. There is no penalty for moving money in and out of a savings account, but frequent large withdrawals might trigger review by the bank for other reasons.
How to find the best interest rate for your situation
The best savings account for you depends on how much money you have, how soon you might need it, and what you are saving for. If you need the money within a few months, a regular savings account or high-yield savings account makes sense because you can withdraw anytime. If you know you will not need the money for two years, a CD might earn you significantly more interest.
To compare accounts, look up the APY at several banks — both online banks and banks in your area. Write down the APY, any monthly fees, any minimum balance requirement, and how often interest is compounded. Calculate what you would earn in one year on your expected balance, then subtract any fees. The account with the highest earnings after fees is usually the best choice.
Keep in mind that interest rates change frequently. A bank offering the highest rate today might lower it next month. You can move your money to a different bank if rates drop significantly, though this takes a few days and requires opening a new account.
Frequently Asked Questions
Do I have to pay taxes on interest I earn?
Yes. Interest earned in a savings account is taxable income. At the end of each year, your bank will send you a form (1099-INT) showing how much interest you earned. You report this on your tax return. The amount of tax you owe depends on your total income and tax bracket.
What if my bank goes out of business — do I lose my interest?
No. The FDIC (Federal Deposit Insurance Corporation) insures deposits at member banks up to $250,000 per account. If a bank fails, the FDIC pays depositors their full balance, including any interest earned up to that point. Your money is protected.
Can interest rates go negative?
In the United States, savings account rates have not gone negative, though they have come close to zero. In some other countries, banks have charged negative rates, meaning you lose money by keeping it in the account. This is unlikely to happen in the U.S., but it is theoretically possible if the Federal Reserve sets rates very low.
Is there a limit to how much interest I can earn?
No. There is no cap on interest earnings. The more money you have in the account and the higher the rate, the more interest you earn. However, interest is taxable, so very high earnings will increase your tax bill.
Why do online banks pay more interest than traditional banks?
Online banks have lower costs because they do not operate physical branches. They pass those savings to customers in the form of higher interest rates. Traditional banks have to pay for buildings, staff, and equipment, so they keep more of the interest they collect from borrowers.