Interest is money your bank pays you for letting them hold your money

When you deposit money into a savings account, the bank lends that money to other customers as mortgages, car loans, and business loans. The bank charges those borrowers interest. In return, the bank pays you a portion of what it collects — that payment is your savings account interest.

The amount you earn depends on three things: how much money you have in the account, what interest rate the bank offers, and how long the money sits there. Banks calculate this daily or monthly, depending on the account, and add the earnings to your balance.

Key Takeaways

  • Interest is calculated as a percentage of your account balance, and the rate varies by bank and account type — some accounts earn nothing, while others currently earn 4% to 5% annually.
  • Banks use either simple interest (calculated once per year) or compound interest (calculated and added to your balance multiple times per year), and compound interest grows faster because you earn interest on your interest.
  • The annual percentage yield (APY) is the real number to compare between banks, because it accounts for how often interest is compounded and shows what you will actually earn in a year.
  • Your interest earnings are taxed as ordinary income, so you will owe federal income tax on the money you earn, and possibly state tax depending on where you live.

How the calculation works: APY versus interest rate

Banks advertise two different numbers, and they are not the same. The interest rate is the percentage the bank pays on your balance. The annual percentage yield (APY) is what you actually earn when compounding is included.

Here is the difference: if a bank offers 4.5% APY on a savings account and you deposit $10,000, you do not earn $450 in one lump sum at the end of the year. Instead, the bank calculates interest monthly (or daily, depending on the account). Each month, it adds a small amount to your balance. The next month, interest is calculated on the new, larger balance — so you earn interest on your interest. By the end of the year, you have earned slightly more than $450.

When you are comparing savings accounts between banks, always look at the APY, not the interest rate. The APY is the honest number because it shows what will actually be in your account after one year.

Simple interest versus compound interest

Simple interest is calculated once and does not change. If a bank paid simple interest at 4.5% on $10,000, you would earn $450 at the end of the year, and that is it. Your balance would be $10,450.

Compound interest is calculated multiple times per year — usually daily or monthly — and each time the interest is added to your balance. The next calculation includes that new balance. This means you earn interest on the interest you already earned.

Using the same $10,000 at 4.5% APY compounded daily: after one month, you have earned roughly $37.50. The next month, interest is calculated on $10,037.50, not the original $10,000. By the end of the year, you have earned about $460 instead of $450. That extra $10 came from compound interest. The more often interest is compounded, the more you earn.

How often interest is added to your account

Banks compound interest on different schedules. Some compound daily, some monthly, and some quarterly. The schedule is listed in the account disclosure document the bank provides when you open the account, or on the bank's website under the account details.

Daily compounding is better than monthly, which is better than quarterly, because your money grows faster. However, the difference is usually small — a few dollars per year on a typical balance. The APY already accounts for the compounding schedule, so when you compare APYs between two banks, you are already comparing the real outcome.

What happens to interest rates when the Federal Reserve changes rates

Savings account interest rates move when the Federal Reserve raises or lowers its benchmark rate. When the Fed raises rates, banks typically raise the rates they offer on savings accounts within days or weeks. When the Fed lowers rates, banks lower savings account rates as well.

However, banks do not have to match the Fed's moves exactly. Some banks raise rates quickly and lower them slowly. Others do the opposite. This is why the same type of account can pay 4.5% at one bank and 3.8% at another — banks compete for deposits by offering different rates.

If you have money in a savings account, your rate can change at any time. Banks must notify you before the change takes effect, but they are allowed to lower your rate. This is different from a certificate of deposit (CD), where your rate is locked in for the entire term.

How taxes affect your interest earnings

Interest you earn on a savings account is taxed as ordinary income. If you earn $500 in interest during the year, that $500 is added to your other income when you file your federal tax return, and you owe income tax on it at your regular tax rate.

Your bank will send you a Form 1099-INT in January if you earned $10 or more in interest during the previous year. You use this form to report the interest on your tax return. Some states also tax interest income, while others do not — this depends on where you live.

This means the real return on your savings is lower than the APY suggests. If you earn 4.5% APY but you are in the 22% federal tax bracket, your after-tax return is closer to 3.5%. This is one reason high-yield savings accounts matter: even after taxes, a higher rate means more money in your pocket.

Why some savings accounts earn nothing

Traditional savings accounts at large banks often pay 0.01% APY or less. This is because those banks have many customers and do not need to compete aggressively for deposits. They can afford to pay almost nothing.

Online banks and credit unions typically pay much higher rates — currently 4% to 5% APY — because they have lower overhead costs and need to attract deposits to grow. The money in your account earns the same way regardless of where it sits, but the rate you receive depends entirely on which institution holds it.

If your savings account is earning less than 1% APY, you are losing purchasing power to inflation. Moving your money to a high-yield savings account at an online bank or credit union is one of the simplest ways to increase what you earn without taking on risk.

Frequently Asked Questions

Can I lose money if interest rates go down?

No. Your account balance will not decrease because rates fell. However, the interest you earn going forward will be lower. If you are in a savings account (not a CD), your rate can change at any time, so you may earn less next month than you do today.

Is interest earned on savings accounts may provide?

The rate is not may provide in a regular savings account — banks can lower it whenever they choose. In a CD, the rate is locked in for the entire term. However, the money itself is insured by the Federal Deposit Insurance Corporation (FDIC) up to $250,000 per account, so you will not lose your principal.

How much interest will I earn on $5,000?

At 4.5% APY, you would earn roughly $225 in one year before taxes. The exact amount depends on how often the bank compounds interest and whether you add or withdraw money during the year. Use your bank's interest calculator or multiply your balance by the APY to estimate.

Why do some banks offer higher rates than others?

Online banks have lower costs than brick-and-mortar branches, so they can afford to pay more. Credit unions are member-owned and often prioritize competitive rates. Large traditional banks have many customers and less pressure to compete on rate, so they pay less.

Does interest compound if I do not touch my account?

Yes. Compounding happens automatically. The bank calculates interest on your balance and adds it to your account whether you log in or not. You do not have to do anything — the interest accrues and grows on its own.