Interest accrues daily, but the bank pays it monthly, quarterly, or annually depending on your account

Your bank calculates how much interest you earn every single day based on your account balance. That daily calculation is accrual—the interest builds up invisibly in the background. But the bank does not add that money to your account when ready. Instead, it holds the accrued interest and deposits it all at once on a schedule: monthly, quarterly, or annually. The schedule depends on your bank and your account type, so check your account agreement or call your bank to find out when yours compounds.

The daily calculation matters because your balance changes constantly. If you have $5,000 on Monday and withdraw $2,000 on Wednesday, the bank calculates interest on $5,000 for two days and $3,000 for the remaining days of that month. The interest you earn that month reflects the actual money you held, day by day.

Key Takeaways

  • Banks calculate interest daily using your current balance, but deposit the earned interest into your account on a schedule—usually monthly, quarterly, or annually.
  • The annual percentage yield (APY) on your account tells you the total interest you will earn in a year if you make no deposits or withdrawals.
  • Withdrawals lower your balance when ready, which reduces the interest you earn that day and every day after until you deposit again.
  • The difference between the interest rate and the APY matters: the rate is what the bank pays, and the APY includes the effect of compounding.

The formula banks use: balance times rate divided by days in the year

Banks use a standard formula to calculate daily interest. They take your account balance, multiply it by the annual interest rate, and divide by 365 (or sometimes 360, depending on the bank's method). That gives them the interest you earn that single day. They repeat this calculation every day of the month or quarter, then add all those daily amounts together and deposit the total.

Example: You have $10,000 in a savings account with a 4.5% annual interest rate. The daily interest is $10,000 × 0.045 ÷ 365 = $1.23 per day. If your balance stays at $10,000 for a full month (30 days), you earn roughly $36.99 in interest. But if you withdraw $5,000 on day 15, the calculation changes: you earn $1.23 per day for 14 days ($17.22), then $0.62 per day for the remaining 16 days ($9.92), for a total of about $27.14 that month.

The exact method varies slightly by bank. Some use the "daily balance method," which is what the example above shows. Others use the "average daily balance method," which averages your balance across the entire period before calculating interest. A few use the "end-of-day balance method," which only counts what you have at the close of business each day. The difference is usually small, but your account agreement will specify which one your bank uses.

APY versus interest rate: why the number on the website is not the whole story

The annual percentage yield (APY) is the interest rate plus the effect of compounding. Compounding means the bank pays interest on your interest. When the bank deposits your accrued interest into your account, that interest becomes part of your balance. The next time interest is calculated, you earn interest on the original balance plus the interest you already earned.

If your account compounds monthly, you earn interest 12 times a year. If it compounds daily, you earn interest 365 times a year. More frequent compounding means more interest on your interest, so a daily-compounding account at 4.5% APY will earn slightly more than a monthly-compounding account at the same rate. The difference grows larger as your balance grows larger and as the interest rate rises.

Banks are required to show you the APY, not just the interest rate, so you can compare accounts fairly. The APY already includes the compounding effect. If a savings account shows 4.5% APY, that is the actual return you will earn over a year if you deposit money and leave it untouched.

When deposits and withdrawals change your daily balance

Every deposit or withdrawal changes the balance the bank uses to calculate interest that day. A deposit made early in the morning increases the balance for the full day. A withdrawal made late in the afternoon still reduces the balance for that day, depending on the bank's cutoff time (usually 2 or 3 p.m. Eastern time for online transactions).

This is why timing matters slightly. If you know interest is being deposited on the 30th of the month, and you have a large deposit coming, depositing a few days before the 30th means that money earns interest before it is credited. Similarly, if you need to withdraw money, waiting until after the interest deposit means you do not lose interest on that money.

In practice, the difference is small—a few cents on most balances—but the principle is real. The bank counts every dollar you hold for every day you hold it.

How interest rates change and what that means for your accrual

Banks change their savings account interest rates frequently, especially when the Federal Reserve changes its benchmark rate. When your bank lowers the rate, the daily interest calculation drops when ready. A 4.5% APY account that drops to 4.0% will earn less interest starting the next day.

Most banks notify you before a rate change, though the notification may come by email or in your online account portal rather than by mail. Check your account agreement to see what notice period your bank is required to give. Some banks give 30 days' notice; others give less. The new rate applies to all interest accrued after the effective date, not retroactively to interest you already earned.

If your bank lowers the rate and you want a higher return, you can move your money to another bank. There is no penalty for closing a savings account and transferring your balance elsewhere. The interest you have already earned stays in your account and moves with you.

Why some accounts earn more interest than others

The interest rate itself depends on the type of account and the bank's business model. High-yield savings accounts typically offer higher rates than traditional savings accounts at the same bank. Money market accounts often offer rates between the two. Certificates of deposit (CDs) usually offer the highest rates, but you have to lock your money away for a set term.

Online banks tend to offer higher rates than brick-and-mortar banks because they have lower overhead costs. A savings account at an online bank might earn 4.5% APY while the same bank's brick-and-mortar branch offers 0.01% APY on a basic savings account. The interest calculation works the same way—daily accrual, periodic deposits—but the rate itself is much higher.

The rate also changes based on the broader economy. When the Federal Reserve raises its benchmark rate, banks compete for deposits by raising their savings rates. When the Fed cuts rates, banks lower their rates too. This is why your APY might be 4.5% one month and 4.0% the next, even if you have done nothing to your account.

What happens to accrued interest if you close your account

Any interest you have accrued but not yet received is still yours. If your bank deposits interest monthly and you close your account on the 15th, you will receive the interest that was accrued from the 1st through the 15th when the bank processes your closure. You do not lose accrued interest by closing early.

The bank will send you the final balance—your original deposit plus all accrued and deposited interest—either as a check or as a transfer to another account, depending on how you close the account. Make sure you have a forwarding address or a receiving account set up before you close, so the bank knows where to send your money.

Frequently Asked Questions

Does my interest earn interest?

Yes, if your account compounds interest. When the bank deposits your accrued interest into your account, that interest becomes part of your balance. The next compounding period, you earn interest on the original balance plus the interest you already earned. This is called compounding, and it is why APY is higher than the stated interest rate.

What if I withdraw money right before interest is deposited?

You still receive the interest you earned up to that point. The bank calculates interest based on your daily balance, so if you held $10,000 for 29 days and withdrew it on day 30, you earn interest on $10,000 for 29 days. The interest deposit happens on schedule, and you receive it in your account or as a transfer, depending on how you closed the account.

Can I lose money if the interest rate drops?

No. Interest rate changes affect only the interest you earn going forward, not the principal balance you deposited. If you have $10,000 and the rate drops from 4.5% to 4.0%, you still have $10,000. You will earn less interest each day after the rate change, but your original deposit is safe.

Why does my bank say interest compounds daily but deposits monthly?

Compounding and depositing are two different things. The bank calculates interest daily (compounding), which means interest earns interest every day. But it deposits the total accrued interest into your account once a month (or quarterly or annually). Both things happen: daily calculation and periodic deposit.

How do I know if my account is earning the best rate available?

Compare your current APY to the rates other banks are offering. Online banks and credit unions often publish their current rates on their websites. If another bank offers a significantly higher rate, you can move your money without penalty. There is no fee for closing a savings account or transferring your balance.