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

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 keeps the difference between what it pays you and what it charges borrowers. That payment to you is called interest.

The amount you earn depends on two things: how much money sits in your account, and the interest rate the bank offers. The interest rate is a percentage. If your account earns 4% annual interest and you have $1,000 in the account for a full year, you earn $40. That $40 gets added to your account balance.

Interest rates change. Banks set their own rates based on what the Federal Reserve does with its benchmark rate, what other banks are offering, and how much they need deposits right now. You might see one rate when you open an account and a different rate three months later.

Key Takeaways

  • Banks pay you interest because they lend out the money you deposit, and interest is your share of what borrowers pay.
  • Your interest earnings depend on your account balance and the interest rate your bank offers, which varies by bank and changes over time.
  • Interest can be calculated and added to your account daily, monthly, or quarterly, depending on the bank's terms.
  • High-yield savings accounts typically pay more interest than traditional savings accounts at the same bank.
  • The interest you earn is taxable income, and your bank will report it to the IRS if it exceeds a certain amount.

How banks calculate and add interest to your account

Banks don't wait until the end of the year to give you all your interest at once. Instead, they calculate interest on a schedule — usually daily, monthly, or quarterly — and add it directly to your account balance. The schedule depends on the bank's terms, which you can find in the account agreement or on the bank's website.

Here's how it works in practice: if your bank calculates interest daily, it divides your annual interest rate by 365 and applies that tiny fraction to your balance each day. At the end of the month or quarter, all those daily calculations are added together and deposited into your account. This means your balance grows slightly every day, even if you don't deposit more money.

The more frequently a bank calculates interest, the slightly more you earn over time — because you earn interest on the interest that was already added. This is called compounding. The difference is usually small with savings accounts, but it adds up over years.

Why interest rates differ between banks and account types

Not all savings accounts pay the same rate. A traditional savings account at a large national bank might pay 0.01% annual interest, while a high-yield savings account at an online bank might pay 4% or higher. The difference comes down to how banks operate and what they need.

Online banks and credit unions often offer higher rates because they have lower overhead costs — no physical branches to maintain, fewer employees to pay. They can afford to pay depositors more because they spend less to run the business. Large national banks with many branches often pay lower rates because their costs are higher.

Within the same bank, different account types earn different rates. A money market account might pay more than a regular savings account. A certificate of deposit (CD) — where you agree to leave money untouched for a set period — typically pays more than either, because the bank knows it can use that money for longer without you withdrawing it.

What happens to your interest when rates change

Banks can change the interest rate on your savings account at any time, and they don't need your permission. When the Federal Reserve raises its benchmark rate, banks usually raise savings rates within days or weeks. When the Fed lowers rates, banks lower savings rates just as quickly — sometimes faster.

You won't lose the interest you've already earned, but new interest will be calculated at the new rate going forward. If you had $5,000 earning 4% and the bank drops the rate to 2%, you keep the interest already added to your account. The $5,000 (plus that interest) will now earn at 2% instead.

This is why some people move their money between banks when rates change. If your current bank drops its rate significantly and another bank is offering much more, you can withdraw your money and move it. There's no penalty for moving savings between banks — the penalty (if any) only applies to CDs and some other products where you've locked in a rate.

How to find out what your account is earning right now

Your bank must disclose the interest rate and how often it's calculated. You can find this information in three places: the account agreement (sometimes called a disclosure statement), your online banking portal, or by calling customer service.

The account agreement is the document you signed or agreed to when you opened the account. It lists the current rate and the terms — how often interest is calculated, whether the rate can change, and any conditions that might affect it. If you opened the account online, you can usually read this document from your bank's website under account documents or statements.

Your online banking portal (the website or app where you check your balance) usually shows your current rate somewhere in the account details section. If you can't find it, customer service can tell you the exact rate in seconds. Ask them to also tell you how often interest is calculated and whether the rate has changed recently.

Interest earned is taxable income

The interest your savings account earns counts as income for tax purposes. If you earn $10 in interest over a year, that $10 is taxable income just like wages from a job.

Your bank tracks how much interest you earn and reports it to the IRS on a form called a 1099-INT if the amount exceeds a certain threshold (currently $10, though this can change). You'll receive a copy of this form, usually by January 31 of the following year. You then report this interest income on your tax return.

Even if your interest earnings don't reach the reporting threshold, you're still required to report them on your tax return if you file one. Keep your bank statements or the 1099-INT your bank sends you so you have the correct amount when you file.

The difference between savings accounts and other ways to earn interest

Savings accounts aren't the only place your money can earn interest. Money market accounts, CDs, and money market funds all pay interest, but with different rules and rates.

A money market account is a hybrid between a checking and savings account. It usually pays more interest than a regular savings account but may have higher minimum balance requirements and limits on how many withdrawals you can make per month.

A certificate of deposit (CD) requires you to leave your money untouched for a set period — three months, one year, five years, or longer. In exchange, the bank pays a higher interest rate than a savings account. If you withdraw the money before the term ends, you pay a penalty (usually a few months' worth of interest).

A money market fund is an investment product, not a bank account. It's riskier than a savings account because the value can go down, but it may pay higher interest. Money market funds are not insured by the FDIC the way bank savings accounts are.

Frequently Asked Questions

Can I lose money in a savings account if interest rates go down?

No. Your account balance never decreases because of a rate change. You keep all the money you deposited and all the interest already earned. The rate change only affects new interest going forward — you'll just earn less interest each month than you did before.

Why does my bank say my interest rate is variable?

A variable rate means the bank can change it without asking you first. Most savings accounts have variable rates. The alternative is a fixed rate, which is locked in for a set period (usually found in CDs). With a variable rate, you should check your account terms periodically to see if the rate has changed.

Is the interest I earn the same as my APY?

Not quite. Your APY (annual percentage yield) is the interest rate plus the effect of compounding — it shows you the total percentage your money will grow in a year. The interest rate alone doesn't account for compounding. Banks must show you the APY so you can compare accounts fairly.

What if I withdraw money before the end of the month — do I lose interest?

No. Interest is calculated based on your balance each day, so you earn interest on the money for however long it sits in the account. If you deposit $1,000 on the first of the month and withdraw it on the 15th, you earn interest for 15 days. You don't lose what you've already earned.

How do I know if my bank's interest rate is competitive?

Compare rates across several banks using their websites or financial comparison sites. Look at the APY (not just the interest rate), and check whether there are any minimum balance requirements or monthly fees that would eat into your earnings. Rates change frequently, so check again every few months if you're considering moving your money.