Treasury bills vs CDs: the highest advertised rate is not the whole comparison

Searches for Treasury bills rates today and CD rates today usually begin with one number: yield. A useful comparison goes further. Treasury bills and certificates of deposit differ in tax treatment, liquidity, insurance structure, purchase process, early-exit cost, and what happens when the investment matures.

Use the CD & Treasury Yield Calculator for a simple term return estimate. Then use the Tax-Equivalent Yield Calculator to compare yields under federal and state tax assumptions.

How Treasury bills work

Treasury bills are short-term U.S. government securities with maturities of one year or less. They are generally sold at a discount or at par, with the investor receiving the face value at maturity. TreasuryDirect explains the auction and maturity structure on its Treasury bills page.

Treasury interest is subject to federal income tax but is generally exempt from state and local income taxes. That can improve the after-tax comparison for residents of states with income tax.

Bills can be purchased through TreasuryDirect or a brokerage. A brokerage may make secondary-market selling easier, but the market price can move before maturity.

How CDs work

A CD is a time deposit issued by a bank or credit union. The institution promises an interest rate for a stated term. Traditional CDs may charge an early-withdrawal penalty; brokered CDs can trade at gains or losses before maturity.

Deposit insurance is a key distinction. Eligible bank deposits are covered by FDIC insurance within applicable ownership categories and limits. Readers should verify the institution and coverage using official FDIC deposit insurance resources. Credit unions may use NCUA coverage instead.

CD interest is generally subject to federal and state income tax. The tax timing and reporting can vary by product, so this page does not provide tax advice.

Compare after-tax yield

Suppose a Treasury bill and CD have similar headline yields. The Treasury’s state-tax treatment may give it a higher after-tax return for some investors. But a CD could still be preferable if it offers a clearly higher rate, simpler banking access, or a maturity that better matches the goal.

The tax-equivalent yield calculator asks for:

  • The tax-exempt or tax-advantaged yield being evaluated.
  • Federal marginal tax-rate assumption.
  • State marginal tax-rate assumption.
  • The competing taxable yield.

It is a screening tool. It does not replace an individualized tax calculation.

Liquidity and early exit

A short-term investment should match the date the money may be needed. Selling a Treasury before maturity introduces market-price risk. Breaking a traditional CD may trigger a penalty. Selling a brokered CD may produce a loss if rates rose after purchase.

An emergency fund should prioritize reliable access. Money for a known expense can be matched to a maturity date. A ladder can divide money across several maturities so everything does not renew at once.

Reinvestment risk

A high short-term yield may not last. When the bill or CD matures, the next available rate could be lower. That is reinvestment risk. Longer maturities can lock a rate for more time but reduce flexibility and may increase price sensitivity if sold early.

The Bond Price Change Calculator illustrates why longer-duration assets can move more when rates change, though Treasury bills themselves have very short duration.

Bottom line

Treasury bills versus CDs is not a universal winner question. Compare after-tax yield, access, maturity, insurance or government backing, early-exit rules, and reinvestment risk. Use official rate and product documents because rates can change daily and promotional terms can hide important conditions.

Educational only. This is not financial, investment, banking, or tax advice.