What Is a Certificate of Deposit?
A certificate of deposit (CD) is a time deposit offered by banks and credit unions that pays a fixed interest rate for a specified term — typically 3 months to 5 years. In exchange for locking up your money until the maturity date, you receive a higher interest rate than a standard savings account. CDs are FDIC-insured up to $250,000 per depositor per institution, making them one of the safest savings vehicles available. The tradeoff is liquidity: withdrawing before maturity triggers an early withdrawal penalty, typically 3–6 months of interest on shorter terms and up to 12 months of interest on longer terms.
The yield on a CD depends on three factors: the stated annual percentage rate (APR), the compounding frequency, and the term length. Daily compounding produces the highest effective yield — the APY — because interest earns interest more frequently. The difference between daily and annual compounding at 5% on a $10,000 deposit over 12 months is small (about $1.25) but becomes more meaningful at higher balances or rates.
APR vs APY: What Banks Advertise
Banks may advertise either the APR (stated rate) or the APY (effective yield after compounding). The APY is always equal to or higher than the APR. The formula is APY = (1 + APR/n)^n - 1, where n is the number of compounding periods per year. At 5% APR, daily compounding produces a 5.127% APY; monthly compounding produces 5.116%; annual compounding leaves APR equal to APY at exactly 5%. When comparing CDs across banks, always compare APY to APY — it's the true measure of what you'll earn.
CD Laddering: Balancing Rate and Liquidity
A CD ladder splits your deposit across multiple terms — for example, equal amounts in 3-month, 6-month, 12-month, 18-month, and 24-month CDs. As each shorter-term CD matures, you reinvest in a new longer-term CD at current rates. This strategy balances two competing goals: capturing higher rates (which usually increase with longer terms) while maintaining regular access to a portion of your funds. If rates rise, your maturing short-term CDs can be reinvested at higher rates quickly. If rates fall, your locked-in longer-term CDs protect against falling yields.
The comparison chart in this calculator shows the interest earned at different terms for your specified rate and deposit — useful for deciding whether the additional interest on a longer term justifies the reduced liquidity. In a flat rate environment, a 5-year CD earns roughly 5x the interest of a 12-month CD. But if rates rise significantly during the 5-year period, you may have been better off laddering short-term CDs.
When CDs Make Sense vs Alternatives
CDs are appropriate when you have a specific sum you know you won't need for a defined period and want a guaranteed, predictable return with no investment risk. They outperform high-yield savings accounts when CD rates exceed HYSA rates, which often happens in rising-rate environments when banks compete aggressively for deposits. CDs underperform HYSA accounts when savings rates climb faster than you can reinvest maturing CDs — a common situation when the Federal Reserve is raising rates rapidly.
Treasury bills and Treasury notes are direct competitors to bank CDs. T-bills offer federal government backing (slightly safer than FDIC-backed bank CDs), state and local tax exemption on interest, and comparable or better yields. For large deposits (above $250,000), T-bills avoid the FDIC limit entirely. For smaller, tax-exempt account holders like IRA custodians, the tax advantage of T-bills is moot, and CDs from credit unions often offer slightly better rates.
Early Withdrawal Penalties and No-Penalty CDs
Early withdrawal penalties vary significantly by institution and term. Short-term CDs (under 6 months) typically charge 3 months of interest; long-term CDs (2–5 years) may charge 12–18 months of interest for early exit. No-penalty CDs — sometimes called liquid CDs — allow withdrawal after a brief holding period (usually 6–7 days) with no penalty. The tradeoff is a lower rate, typically 0.25–0.50% below standard CD rates. No-penalty CDs are worth considering for emergency fund money that you want earning more than a savings account but might need to access.