What a CD actually does

A certificate of deposit (CD) is an agreement between you and a bank: you give them a sum of money, they promise to pay you back that exact amount plus interest after a set period of time. You cannot touch the money during that period without paying a penalty. That is the entire mechanism.

The bank uses your money during that time—lending it out, investing it—and shares a portion of what they earn with you as interest. Because the bank knows exactly when they will have to give your money back, they can afford to pay you more interest than a regular savings account offers. The tradeoff is that your money is locked away.

A CD is not an investment in the traditional sense. You are not buying a piece of a company or betting on a market. Your principal—the amount you deposit—is may provide to stay the same. The interest rate is fixed and will not change, no matter what happens to the economy or the bank's other rates.

Key Takeaways

  • You deposit a lump sum and agree not to withdraw it for a specific period, called the term, which ranges from a few months to several years.
  • The bank pays you a fixed interest rate that is locked in on the day you open the CD and does not change for the entire term.
  • If you withdraw money before the term ends, you pay an early withdrawal penalty, which is usually a certain number of months' worth of interest.
  • Your deposit is insured by the FDIC up to $250,000, so your principal is protected even if the bank fails.
  • CDs pay more interest than savings accounts because you are giving up access to your money for a defined period.

The term: how long your money stays locked

When you open a CD, you choose how long the money will stay in the account. This is called the term. Common terms are 3 months, 6 months, 1 year, 2 years, 3 years, and 5 years. Some banks offer shorter terms (30 days) or longer ones (10 years), but these are less common.

The longer the term you choose, the higher the interest rate the bank will usually offer. A 5-year CD will pay more than a 1-year CD because the bank gets to use your money for longer. You are being paid for that commitment.

The term is not negotiable. You pick from what the bank offers. Once you deposit your money, that term is set. On the day the term ends—called the maturity date—the bank will either return your money plus interest to your account, or automatically roll it into a new CD at the current rate, depending on what you chose when you opened it.

Interest rates and how they are calculated

The interest rate on a CD is fixed, meaning it does not change. If you open a 2-year CD at 4.50%, you will earn 4.50% per year for the entire 2 years, even if the bank raises or lowers its rates next month.

Banks calculate CD interest in different ways. Most use annual percentage yield (APY), which accounts for compounding—meaning you earn interest on your interest. If your CD compounds monthly, the bank calculates and adds interest to your account each month, and the next month's interest is calculated on the larger balance. This compounds throughout the term.

The actual dollar amount you earn depends on three things: how much you deposit, what the APY is, and how long the term is. A $10,000 CD at 4.50% APY for 1 year will earn roughly $450 in interest (before any taxes). A $10,000 CD at the same rate for 2 years will earn roughly $920, because of compounding.

What happens if you need the money early

If you withdraw money from a CD before the maturity date, you pay an early withdrawal penalty. This penalty is usually expressed as a number of months of interest. A common penalty is 6 months of interest, meaning if you withdraw early, the bank subtracts 6 months' worth of what you would have earned and keeps that amount.

The penalty varies by bank and sometimes by the term length. A 3-month CD might have a 1-month penalty; a 5-year CD might have a 12-month penalty. You should always ask what the penalty is before you open the CD, because it is the cost of changing your mind.

If you withdraw early and the penalty is larger than the interest you have earned so far, you will lose some of your principal. For example, if you open a CD, deposit $5,000, earn $100 in interest over 2 months, then withdraw, and the penalty is 6 months of interest (roughly $300), the bank will subtract $300 from your account. You will get back $4,800 instead of $5,000.

This is why CDs are best for money you know you will not need. If there is any chance you might need the funds, a regular savings account is safer, even though it pays less interest.

FDIC insurance and your protection

Money in a CD is insured by the Federal Deposit Insurance Corporation (FDIC) up to $250,000 per depositor, per bank. This means if the bank fails, the FDIC will return your principal and any interest earned up to that limit.

This protection applies only to the principal and accrued interest. It does not protect you from early withdrawal penalties—if you withdraw early and pay a penalty, that penalty is your loss, not the bank's responsibility.

If you have more than $250,000 to deposit, you can open CDs at different banks to stay within the insurance limit at each one. Some people also open CDs in different names (for example, one in their name alone, one jointly with a spouse) because each account is insured separately up to $250,000.

When the CD matures: what happens next

On the maturity date, the bank will credit your principal plus all interest earned to your account. You now have access to the full amount with no penalty. The money will sit in your account (usually a checking or savings account linked to the CD) until you decide what to do with it.

Many banks offer an automatic renewal option. If you choose this when you open the CD, the bank will automatically roll the full balance (principal plus interest) into a new CD with the same term at the current interest rate. You do not have to do anything. If you do not want automatic renewal, the money will simply be transferred to your linked account and stay there.

You have a grace period—usually 7 to 10 days after maturity—to withdraw the money or change your mind about renewal without penalty. If the bank automatically renews and you decide you do not want the new CD, you can withdraw during this window without the early withdrawal penalty. After the grace period ends, the new CD is locked in.

CDs versus savings accounts: why the difference matters

A regular savings account lets you deposit and withdraw money whenever you want, but it pays a lower interest rate—often less than 1% APY. A CD locks your money away but pays significantly more, sometimes 4% to 5% APY depending on the term and the bank.

The choice depends on your situation. If you have money you will not need for a year or more, a CD pays you more for waiting. If you might need the money sooner, a savings account is more flexible, even though you earn less. Some people split the difference: they put money they definitely will not need into a CD and keep an emergency fund in a savings account.

CDs also differ from bonds and stocks. Those are investments where the value can go up or down. A CD is a may provide return—you know exactly what you will earn before you open it.

Frequently Asked Questions

Can I add more money to a CD after I open it?

No. A CD is a fixed deposit. Once you open it with a certain amount, you cannot add to it. If you want to deposit more money, you would need to open a separate CD. Some banks let you open multiple CDs at the same time with different amounts.

What happens to my interest if I withdraw early?

You lose some or all of it. The bank subtracts the early withdrawal penalty from your account. If the penalty is larger than the interest you have earned, you will also lose part of your principal. This is why early withdrawal is costly.

Do I pay taxes on CD interest?

Yes. CD interest is taxable income in the year it is earned. The bank will send you a 1099-INT form at tax time showing how much interest you earned. You report this on your tax return. This is true even if you do not withdraw the money.

Should I choose a longer term to get a higher rate?

That depends on whether you can afford to lock the money away. A 5-year CD pays more than a 1-year CD, but if you need the money in 2 years, the early withdrawal penalty will eat into your gains. Choose a term that matches when you actually need the money.

What if interest rates go up after I open my CD?

Your rate stays the same. You are locked in at the rate you opened with. This is a risk of CDs—if rates rise, you will wish you had waited. But if rates fall, you are protected by your higher rate. This is why some people open CDs in a ladder, spreading deposits across different terms so they can take advantage of rate changes as CDs mature.