Interest is paid by depositing money directly into your account on a schedule set by your bank

When a bank pays interest on your savings account, it deposits the earned amount into that same account. You do not receive a separate check or transfer—the interest straightforward appears as a credit to your balance. The timing and frequency depend on your bank's terms: some pay interest monthly, others quarterly, and a few daily (though the deposit happens less often). The amount you earn depends on three things: how much money sits in the account, the interest rate your bank offers, and how long the money stays there.

The interest rate itself is set by your bank and can change. Banks are not required to notify you before lowering a rate, though most do. If rates rise, your bank may or may not raise yours—that is a business decision. You can see your current rate in your account agreement or online banking portal, usually labeled as APY (Annual Percentage Yield) or APR (Annual Percentage Rate). APY is the more useful number because it accounts for how often interest compounds.

Key Takeaways

  • Interest deposits directly into your savings account on a schedule your bank sets—usually monthly or quarterly—not as a separate payment.
  • The amount you earn is calculated using your account balance, the interest rate, and the compounding frequency, which determines how often interest earns interest.
  • Your bank can lower your interest rate at any time without advance notice, though most banks notify customers when rates change.
  • High-yield savings accounts at online banks typically pay 4 to 5 percent APY, while traditional brick-and-mortar banks often pay under 0.5 percent.

How the calculation actually works

Banks use a formula to calculate interest, and the math depends on whether interest compounds—meaning interest earns interest. Most savings accounts compound daily, which means the bank calculates interest on your balance each day, and that interest gets added to your balance so the next day's calculation includes it.

Here is a concrete example. Suppose you have $10,000 in an account earning 4.5 percent APY, compounded daily. The bank divides the annual rate by 365 days: 4.5 ÷ 365 = 0.0123 percent per day. On day one, it calculates interest on $10,000: $10,000 × 0.000123 = $1.23. That $1.23 gets added to your balance, so on day two the bank calculates interest on $10,001.23. By the end of the year, you will have earned approximately $461 (not exactly $450, because of compounding). The more frequently interest compounds, the more you earn.

The APY figure your bank shows you already accounts for compounding, so you do not have to do this math yourself. If a bank says 4.5 percent APY, you will earn roughly that amount over a year if you leave the money untouched. If you withdraw money mid-month, you earn less because the balance was lower for part of the period.

When interest actually hits your account

The bank calculates interest daily, but it does not deposit it daily. Instead, it posts the accumulated interest on a schedule: usually the last day of the month, the last day of each quarter, or sometimes on the anniversary of your account opening. You can see when interest posts by checking your account statement or transaction history—it will show as a deposit with a label like "Interest Paid" or "Interest Credit."

The timing matters if you are trying to reach a minimum balance. Some banks require you to maintain a certain balance to earn the advertised rate. If your balance drops below that minimum on any day during the month, you may earn a lower rate for that entire period, even if you bring the balance back up before interest posts. Read your account agreement to see whether your bank uses this rule.

If you close your account before interest posts, you will not lose the interest you have already earned—it will post to your account before closure, or the bank will send it to you. However, if you close the account on a day when interest has not yet posted, you may miss that month's payment. Call your bank before closing to confirm the posting date.

Why interest rates vary so much between banks

A savings account at a large brick-and-mortar bank might pay 0.01 percent APY, while an online bank pays 4.5 percent APY on the same $10,000. The difference is not a mistake—it reflects how banks make money and what they do with deposits.

Banks earn money by lending out customer deposits at higher rates than they pay in interest. A bank that pays you 0.01 percent can lend that money at 5 or 6 percent and keep the difference. Online banks have lower overhead costs (no physical branches, fewer employees), so they can afford to pay higher rates and still profit. Traditional banks have higher costs, so they pay less interest to offset those expenses.

The Federal Reserve's interest rate also influences what banks pay. When the Fed raises its benchmark rate, banks gradually raise savings rates. When the Fed cuts rates, banks cut rates too—sometimes quickly, sometimes slowly. Your bank's rate is not locked in; it can change monthly or even more often.

How taxes affect the interest you keep

Interest earned on a savings account is taxable income. If you earn $100 in interest during a calendar year, you owe federal income tax on that $100 (and possibly state income tax, depending on where you live). Your bank will send you a 1099-INT form in January showing how much interest you earned the previous year. You report that amount on your tax return.

The tax you owe depends on your overall income and tax bracket. If you are in the 22 percent tax bracket and earn $100 in interest, you will owe approximately $22 in federal tax on that interest. The bank does not withhold this tax automatically—you pay it when you file your return. If you earn more than $10 in interest during the year, the bank must issue a 1099-INT; if you earn less, no form is required, but you still owe tax on it.

This is why the difference between a 0.01 percent account and a 4.5 percent account matters. On $10,000, you earn $1 at 0.01 percent (roughly $0.78 after tax) versus $450 at 4.5 percent (roughly $351 after tax, depending on your bracket). The higher rate account leaves you with significantly more money even after taxes.

What happens if you withdraw money before interest posts

If you withdraw money from your savings account before the interest posting date, you still earn interest on the balance for the days the money was there. The bank calculates interest based on your daily balance, so if you had $10,000 for 20 days and then withdrew it, you earn interest only on those 20 days' worth of balance.

Some older savings accounts have a different rule: they require you to maintain the minimum balance through the end of the month to earn any interest at all. If your balance drops below the minimum on day 29 of a 31-day month, you earn zero interest for the entire month. This is rare now, but it exists in some legacy accounts. Check your account agreement to see which rule applies to you.

If you are moving money frequently between accounts, the daily compounding method works in your favor. Money earns interest for every day it sits in the account, so even a few days of deposits add up over time.

Frequently Asked Questions

Can my bank lower my interest rate without telling me?

Yes. Banks can change savings rates at any time without advance notice, though most notify customers when rates drop. You can check your current rate in your online banking portal or account agreement. If your rate drops significantly, you can move your money to a different bank that offers a higher rate.

Why does my interest seem lower than the APY the bank advertised?

The most common reason is that your balance was lower than expected during the month. Interest is calculated on your daily balance, so if you withdrew money mid-month, you earned less. Also, if you just opened the account, you may not have had money in it for the full month. Check your statement to see the exact dates interest was calculated.

Do I have to report interest under $10 on my taxes?

The bank does not have to send you a 1099-INT form if you earn less than $10, but you still owe tax on that interest. Report it on your tax return even if you do not receive a form. The IRS expects you to report all interest income.

What is the difference between APY and APR on a savings account?

APY (Annual Percentage Yield) includes the effect of compounding, so it shows the real amount you will earn. APR (Annual Percentage Rate) does not account for compounding. For savings accounts, APY is the number that matters—it tells you what you will actually make over a year.

If I close my account, do I lose the interest I earned?

No. Interest that has already posted to your account is yours to keep. If you close the account before the monthly interest posting date, you may miss that month's interest payment. Contact your bank before closing to confirm when the next interest posts.