What determines your CD interest earnings

The amount of interest you earn on a CD depends on three things: the interest rate the bank offers, how much money you deposit, and how long you lock that money away. A bank that offers 4.50% annual interest on a one-year CD will pay you more than a bank offering 3.75% on the same deposit—but only if you leave the money untouched for the full year.

Interest rates change constantly. The rate available today may be different tomorrow, and rates vary widely between banks. A large national bank might offer 3.00% on a one-year CD while an online bank offers 4.75% for the exact same product. The difference matters: on a $10,000 deposit, that gap means $175 more in your pocket over one year.

The length of the CD also shifts the rate. Most banks pay higher rates for longer commitments. A six-month CD might pay 3.50%, while a five-year CD from the same bank might pay 4.80%. The bank is paying you extra because you're agreeing to lock your money away for longer.

Key Takeaways

  • Your earnings equal the interest rate multiplied by your deposit amount and the time held, so a higher rate or larger deposit increases what you earn.
  • Interest rates vary between banks by as much as 1.5 percentage points for the same CD length, making it worth checking multiple banks before depositing.
  • Longer CD terms usually pay higher rates than shorter ones from the same bank, but you cannot access the money without paying an early withdrawal penalty.
  • Interest compounds on most CDs, meaning you earn interest on your interest, though the effect is small on shorter terms.
  • The interest you earn is taxable income, so your actual take-home amount depends on your tax bracket.

How to calculate what you'll earn

The basic calculation is straightforward: multiply your deposit by the annual interest rate, then multiply by the number of years. A $5,000 deposit at 4.00% for one year earns $200. The same deposit at 4.00% for two years earns $400 (before compounding, which adds a small amount on top).

Most banks compound interest daily or monthly, which means you earn interest on the interest that's already been added to your account. On a one-year CD this effect is tiny—maybe a few dollars on a $5,000 deposit. On a five-year CD it becomes more noticeable. A $10,000 deposit at 4.50% compounded daily grows to about $10,237 after one year, not $10,450, because the compounding happens gradually throughout the year rather than all at once.

Your bank will show you the Annual Percentage Yield (APY) on every CD product. This is the rate that already includes the effect of compounding, so you can compare it directly between banks without doing any math yourself. If one bank shows 4.50% APY and another shows 4.48% APY on the same CD length, the first bank will pay you slightly more.

Why rates differ between banks and CD lengths

Banks set CD rates based on what they can earn by lending out the money you deposit. When the Federal Reserve raises interest rates, banks can charge borrowers more, so they can afford to pay depositors more. When the Fed cuts rates, CD rates fall too. This is why CD rates were near zero in 2020 and 2021, then climbed sharply in 2022 and 2023.

Online banks typically pay higher rates than brick-and-mortar banks because they have lower overhead costs. They don't maintain physical branches, so they can pass savings along to depositors. A large national bank with thousands of branches might offer 3.50% on a one-year CD, while an online bank with no branches offers 4.75% for the same product.

Longer CDs pay more because the bank wants to lock in your money for a longer period. If you commit to five years, the bank knows it can lend that money out for five years without worrying you'll withdraw it. In exchange, they pay you a higher rate. If you only commit to three months, the bank faces more uncertainty about future rates, so they pay less.

What happens to your earnings if you withdraw early

If you withdraw money from a CD before the term ends, the bank charges an early withdrawal penalty. This penalty is usually expressed as a number of months of interest. A CD with a three-month penalty means you lose three months' worth of interest if you cash out early.

On a $10,000 CD earning 4.50% annually with a three-month penalty, the monthly interest is about $37.50. If you withdraw after six months, you'd lose $112.50 in penalties, leaving you with $10,225 instead of $10,337. The penalty can sometimes be large enough that you end up with less than you started with, especially on longer-term CDs.

This is why CDs work best for money you genuinely won't need. If there's any chance you'll need the funds, a regular savings account with no withdrawal restrictions makes more sense, even if the interest rate is lower.

Comparing rates across different CD terms

Banks offer CDs in many different lengths: three months, six months, one year, 18 months, two years, three years, and five years are common. Each length has its own interest rate. Generally, longer terms pay more, but not always by much.

A bank might offer 4.00% on a one-year CD and 4.25% on a two-year CD—only a 0.25 percentage point difference. On a $5,000 deposit, that's $12.50 extra per year for locking your money away twice as long. Whether that trade-off makes sense depends on whether you might need the money.

Some banks offer "CD ladders" as a strategy: you deposit money into multiple CDs with different maturity dates so that some of your money becomes available each year. This lets you earn higher rates on longer terms while still having regular access to portions of your money. A $10,000 ladder might be five $2,000 CDs maturing in one, two, three, four, and five years.

How taxes affect your actual earnings

CD interest is taxable income. The bank will send you a 1099-INT form at tax time showing how much interest you earned, and you'll owe federal income tax on that amount. Depending on your tax bracket, you might owe 10%, 22%, 24%, or more of your earnings to the IRS.

If you earn $200 in CD interest and you're in the 24% tax bracket, you'll owe $48 in federal taxes on that interest. Your actual take-home is $152, not $200. State income tax may apply too, depending on where you live.

This is why the advertised rate isn't the same as your real earnings. A 4.50% CD sounds good until you realize that after taxes, your real return might be closer to 3.40% depending on your situation. High-yield savings accounts and money market accounts work the same way—the interest is taxable.

When a CD makes sense versus other options

A CD makes sense when you have money you won't need for a specific period and you want a may provide rate. You know exactly what you'll earn, and the FDIC insures deposits up to $250,000, so there's no risk of losing your principal.

A regular savings account makes more sense if you might need the money before the CD matures. The interest rate is usually lower, but you can withdraw without penalty. A money market account splits the difference—slightly higher rates than savings but lower than CDs, with some withdrawal flexibility.

If you're saving for something specific—a down payment in three years, a car purchase in 18 months—a CD with a matching term locks in your rate and removes the temptation to spend the money. If you're building an emergency fund, a high-yield savings account is better because you need quick access.

Frequently Asked Questions

Can I earn more interest by depositing more money?

Yes, but only proportionally. A $20,000 deposit at 4.50% earns twice as much as a $10,000 deposit at the same rate. However, most banks don't offer higher rates for larger deposits—the rate is the same whether you deposit $1,000 or $100,000. Some banks do offer slightly better rates for very large deposits, but this is uncommon.

What's the difference between APR and APY on a CD?

APR (Annual Percentage Rate) is the simple interest rate without compounding. APY (Annual Percentage Yield) includes the effect of compounding. Banks are required to show you the APY, which is the number that matters for comparing CDs. APY is always equal to or slightly higher than APR.

Do I have to pay taxes on CD interest while the CD is still open?

No. You pay taxes on the interest in the year it's earned, but you don't have to pay until tax time. The bank reports the interest on a 1099-INT form sent to you in January. You include that amount on your tax return for the year the interest was earned, even if the CD hasn't matured yet.

Will my CD rate change if interest rates drop?

No. Once you lock in a rate, it stays the same for the entire CD term, even if the bank lowers its rates the next day. This is the main benefit of a CD—you're protected from rate drops. The downside is you're also locked out of rate increases.

Is there a minimum deposit required for a CD?

Most banks require a minimum deposit, typically $500 to $2,500, though some online banks have no minimum. A few banks offer CDs with $1 or $100 minimums. Check the specific bank's requirements before opening a CD.