How banks calculate the interest you earn
A savings account interest rate is a percentage of your balance that the bank pays you each year for letting them use your money. The bank borrows your deposit, lends it out to other customers at a higher rate, and shares a portion of that profit with you as interest.
The actual dollar amount you earn depends on three things: your account balance, the interest rate the bank offers, and how often the bank compounds (adds earned interest back into your account). If you have $1,000 in an account earning 4.5% annual percentage yield (APY), you will earn roughly $45 in a year, though the exact amount varies slightly depending on whether the bank compounds daily, monthly, or quarterly.
Most savings accounts compound interest daily, meaning the bank calculates what you owe each day and adds it to your balance. That daily interest then earns interest itself the next day — a small effect called compounding. Over months and years, compounding makes a meaningful difference, especially at higher rates.
Key Takeaways
- Banks pay you interest as a percentage of your balance, calculated daily or monthly depending on the account, and the rate changes based on what the Federal Reserve does.
- Annual Percentage Yield (APY) is the rate you should compare between banks because it includes the effect of compounding, while APR does not.
- Online banks typically offer higher rates than brick-and-mortar banks because they have lower overhead costs and pass the savings to depositors.
- Your rate can drop without warning if the Federal Reserve cuts rates, so checking your bank's current rate every few months helps you know whether to move your money.
- The interest you earn is taxable income, and your bank will send you a 1099-INT form at tax time if you earned $10 or more in interest during the year.
Why rates change and what controls them
The Federal Reserve, the central bank of the United States, sets a target range for the federal funds rate — the interest rate banks charge each other for overnight loans. When the Fed raises this rate, banks raise the rates they offer on savings accounts. When the Fed cuts rates, banks cut savings rates too, often within days.
Banks are not required to pass along every Fed rate change to savers. A bank might keep its savings rate flat even after the Fed raises rates, pocketing the extra profit. This is why two banks can offer very different rates on the same day. Online banks tend to raise rates faster than traditional banks because they compete heavily on rate to attract deposits, while brick-and-mortar banks rely more on branch locations and customer loyalty.
The Fed does not set savings account rates directly — it influences them by changing the cost of money in the banking system. Your rate is ultimately whatever your specific bank decides to offer. This means you should check your bank's current rate every few months, because it can drop without notice.
APY versus APR: which number to use when comparing
Annual Percentage Yield (APY) is the rate you should use to compare savings accounts. APY includes the effect of compounding — it shows you the actual percentage of your balance you will earn in a year if you leave the money untouched.
Annual Percentage Rate (APR) is a different number that does not include compounding. APR is used for loans and credit cards, not savings accounts. If a bank quotes you an APR on savings, convert it to APY or ask for the APY instead, because APR will understate what you actually earn.
For example, a savings account might advertise a 4.5% APY. That means if you deposit $10,000 and make no withdrawals or deposits, you will have roughly $10,450 after one year. The exact amount depends on how often the bank compounds, but APY already accounts for that, so you can compare APY numbers directly between banks without doing any math.
How compounding frequency affects your earnings
Compounding means the bank adds your earned interest to your balance, and then the next period's interest is calculated on the larger balance. The more often a bank compounds, the more you earn, though the difference is usually small.
Most savings accounts compound daily, which is the most common and most favorable to you. Some accounts compound monthly or quarterly. At a 4.5% APY, the difference between daily and monthly compounding is less than $1 per year on a $10,000 balance, but it adds up over time and across larger balances. The APY number already reflects the compounding frequency, so you do not need to calculate it yourself — just compare APY to APY.
High-yield savings accounts (HYSAs) almost always compound daily. Money market accounts and certificates of deposit (CDs) vary, but most also compound daily. Regular savings accounts at traditional banks often compound daily too, though they offer much lower rates.
Why online banks offer higher rates than traditional banks
Online banks have no physical branches, no tellers, and no regional offices. Their overhead is a fraction of what a traditional bank spends. Because they have lower costs, they can afford to pay higher interest rates on savings and still make a profit. A traditional bank might offer 0.01% APY on a savings account, while an online bank offers 4.5% or higher on the same type of account.
Online banks are insured by the Federal Deposit Insurance Corporation (FDIC) just like traditional banks, so your money is equally safe. The trade-off is that you cannot walk into a branch to deposit cash or speak to a teller in person. Most online banks let you deposit checks by phone camera and transfer money electronically, which works for most people.
If you keep most of your savings in a traditional bank because of convenience or habit, you are likely earning far less interest than you could. Moving money to an online savings account or high-yield savings account takes about 15 minutes and can add hundreds of dollars per year in interest on a large balance.
How to lock in a rate with a CD if rates might drop
A certificate of deposit (CD) is a savings product where you agree to leave your money untouched for a set period — usually three months to five years — in exchange for a fixed interest rate. If rates drop after you open the CD, your rate stays the same. If rates rise, you are stuck with the lower rate unless you withdraw early and pay a penalty.
CDs make sense if you believe rates are about to fall and you want to lock in the current rate. They also work well for money you know you will not need for a specific period, like a down payment you are saving for over two years. The tradeoff is that your money is not accessible without a penalty, and the penalty can be substantial — sometimes three to six months of interest.
The CD ladder strategy lets you split your savings across multiple CDs with different maturity dates. For example, you might open five one-year CDs, one maturing each month for the next five months. As each CD matures, you can open a new five-year CD at whatever the current rate is. This gives you some flexibility while still locking in rates for longer periods.
Tax treatment of savings account interest
Interest you earn on a savings account is taxable income. The bank reports it to the IRS on a 1099-INT form if you earned $10 or more during the year. You must report this interest on your tax return, and it is taxed at your ordinary income tax rate — the same rate as wages or salary.
If you earned $100 in interest and you are in the 22% federal tax bracket, you will owe roughly $22 in federal income tax on that interest (plus any state income tax). This is why the real return on your savings is lower than the APY. A 4.5% APY becomes roughly 3.5% after taxes if you are in the 22% bracket.
Some people use tax-advantaged accounts like a Roth IRA or Health Savings Account (HSA) to earn interest without paying tax on it. These accounts have contribution limits and rules about when you can withdraw, but the tax savings can be significant if you have a large balance.
What happens to your rate when you make deposits or withdrawals
Your interest rate does not change when you deposit or withdraw money. The rate stays the same as long as you keep the account open. However, the amount of interest you earn each month changes based on your balance. If you deposit $5,000, next month's interest is calculated on a larger balance, so you earn more. If you withdraw $5,000, next month's interest is calculated on a smaller balance, so you earn less.
Some savings accounts have tiered rates, where the interest rate increases if your balance reaches certain thresholds. For example, a bank might offer 0.5% APY on balances under $25,000 and 1.0% APY on balances of $25,000 or more. If your balance crosses that threshold, your rate jumps up. These tiered accounts are less common now because online banks offer flat high rates to all customers regardless of balance.
Frequently Asked Questions
Can I lose money in a savings account if interest rates drop?
No. Your balance never decreases because of a rate drop. If your rate falls from 4.5% to 2.0%, you will earn less interest going forward, but the money you already have stays in the account. You only lose purchasing power if inflation is higher than your interest rate, which means your money buys less over time.
Is a savings account or a CD better if I think rates will go up?
A savings account is better if rates are rising, because your rate will rise with them. A CD locks you in at the current rate, so if rates jump next month, you cannot take advantage of it without paying an early withdrawal penalty. Keep savings in a high-yield savings account if you expect rates to climb.
How often does the bank add interest to my account?
Most banks compound and post interest daily, meaning they calculate it every day and add it to your balance monthly or quarterly. Some banks post less frequently. Check your account agreement or call your bank to confirm. Daily compounding is standard at online banks and high-yield savings accounts.
What is the difference between a savings account and a money market account?
A money market account usually offers a higher interest rate than a regular savings account, but it may require a larger minimum balance and limit how many withdrawals you can make per month. Both are FDIC insured. Money market accounts sometimes offer tiered rates based on your balance, while savings accounts usually offer a flat rate.
Do I have to report savings account interest on my taxes if I earned less than $10?
No. Banks only send a 1099-INT form if you earned $10 or more. However, you should still report any interest you earned, even if it is under $10, because it is taxable income. The $10 threshold is just when the bank is required to report it to the IRS.