Interest accrues by adding a small percentage of your balance to your account on a set schedule

Interest is money the bank pays you for letting them hold your money. The bank lends your deposits to other customers and makes money from the interest those customers pay on loans. In return, the bank shares a portion of that income with you.

Accrual means the interest is calculated and added to your account. Most savings accounts accrue interest daily but credit it (actually deposit it into your account) monthly. This means the bank calculates how much you owe every single day, but you don't see the money appear until the end of the month.

The amount of interest you earn depends on three things: how much money you have in the account, what interest rate the bank is offering, and how long your money sits there. A higher balance, a higher rate, or a longer time period all mean more interest earned.

Key Takeaways

  • Interest accrues daily on most savings accounts, meaning the bank calculates your earnings every day based on your current balance.
  • You typically see the interest credited to your account once a month, even though it was calculated daily.
  • The interest rate varies by bank and changes over time, so the amount you earn is not fixed.
  • Compound interest means you earn interest on your interest, which is why money grows faster the longer it sits in the account.

How the daily accrual calculation works

Banks use a formula to calculate how much interest you earn each day. They take your account balance, divide it by 365 (or sometimes 360), multiply by the annual interest rate, and that gives them the interest for one day.

Here is a concrete example. If you have $1,000 in an account with a 4.00% annual interest rate, the bank calculates: $1,000 ÷ 365 × 0.04 = about $0.11 per day. That $0.11 accrues every single day. After 30 days, you have accrued about $3.30 in interest, even though you have not seen it in your account yet.

Different banks may use slightly different methods. Some use 360 days instead of 365, which changes the calculation slightly. Some use the average daily balance if your balance changes throughout the month. The difference is usually small, but it is worth asking your bank how they calculate interest if you want to know exactly.

When accrued interest actually appears in your account

The interest you accrue throughout the month is credited to your account on a specific date, usually the last day of the month or the first day of the next month. On that date, all the daily accruals are added together and deposited as a lump sum.

Once the interest is credited, it becomes part of your balance. This matters because starting the next day, you earn interest on that interest. If you had $1,000 and earned $3.30 in interest, your new balance is $1,003.30, and the bank now calculates daily interest on $1,003.30, not just the original $1,000.

If you withdraw money before the interest is credited, you lose the accrued interest for that month. For example, if you withdraw $500 on the 28th of the month and the interest credits on the 30th, the bank recalculates the interest based on the lower balance for those last two days. You do not lose interest you already earned, but you earn less interest on the days after the withdrawal.

Why interest rates change and what that means for you

The interest rate your bank offers is not permanent. Banks change their rates based on what the Federal Reserve does with its own interest rates. When the Federal Reserve raises rates, banks usually raise the rates they offer on savings accounts. When the Federal Reserve lowers rates, banks usually lower their savings rates too.

This means the amount of interest you earn can go up or down month to month. If your bank was paying 4.00% one month and drops to 3.50% the next month, your daily accrual will be smaller going forward. The interest you already earned stays in your account, but future earnings will be based on the new, lower rate.

Some banks change rates frequently, and some change them rarely. High-yield savings accounts tend to change rates more often because they are designed to track market conditions closely. Traditional savings accounts at large banks may change rates less frequently. You can check your bank's website or call to find out what your current rate is.

Compound interest: earning interest on your interest

Compound interest is the reason your money grows faster over time. It happens automatically in a savings account because the interest you earn gets added to your balance, and then you earn interest on that new, larger balance.

In month one, you earn interest on $1,000. In month two, you earn interest on $1,000 plus the interest from month one. In month three, you earn interest on all of that. The longer your money stays in the account untouched, the more powerful this effect becomes.

The difference between straightforward interest (earning interest only on your original deposit) and compound interest (earning interest on your interest) is small in the first few months but grows significantly over years. This is why starting a savings account early, even with a small amount, can lead to more growth than starting later with a larger amount.

How to find out your actual interest earnings

Your bank statement shows the interest you earned each month. Look for a line item that says "Interest Paid" or "Interest Credited." This tells you exactly how much was added to your account that month.

You can also log into your online banking and check your transaction history. The interest deposit will appear as a credit to your account on the day it was credited. If you want to track your interest earnings over time, you can write down the monthly amount or save your statements.

Some banks also provide an annual summary showing total interest earned for the year. This is useful for tax purposes if you earned more than $10 in interest, since you may need to report it on your tax return. Your bank will send you a form called a 1099-INT if you earned $10 or more in interest during the year.

What happens to your interest if you close the account

If you close your savings account before the interest is credited for the month, you lose the accrued but uncredited interest. The bank does not pay you for interest that has not yet been officially added to your account.

This is one reason to check the interest crediting date before you close an account. If interest credits on the 30th and you are closing on the 28th, you might want to wait two days to capture that month's interest. The amount is usually small, but it is your money.

Interest that has already been credited stays with you. If you withdraw the money or transfer it to another account, the interest you earned is part of that withdrawal or transfer.

Frequently Asked Questions

Can I lose money in a savings account because of interest?

No. Interest is money the bank adds to your account, never subtracts from it. Your balance can only go down if you withdraw money or if fees are charged. Interest always increases your balance or stays the same if the rate is zero.

Why is my interest so small if the rate is 4%?

The 4% is an annual rate, meaning that is how much you would earn if you left $1,000 in the account for a full year. You earn one-twelfth of that each month. On $1,000 at 4% annually, you earn about $3.33 per month, or about $0.11 per day. Smaller balances earn proportionally smaller amounts.

Does interest accrue on money I just deposited?

Yes, but the timing depends on your bank. Some banks start accruing interest the day you deposit money. Others wait until the next business day. Check with your bank about their specific policy, especially if you are depositing money near the end of the month.

What if my bank offers 0% interest?

Some savings accounts, particularly at very large traditional banks, offer little to no interest. Your money is still safe and insured, but you earn nothing for keeping it there. High-yield savings accounts at online banks or credit unions typically offer higher rates if earning interest matters to you.

Does the interest rate ever go negative?

In the United States, savings account interest rates do not go negative. The worst case is 0%, meaning you earn nothing but do not lose money. In some other countries, negative rates exist, but that is not how U.S. savings accounts work.