Treasury Bill Calculator
2026 rulesTurn a T-bill's auction discount rate into its price, real yield and after-tax interest.
Your numbers
T-bill interest is free of state tax.
Result
Investment rate (annual yield)
- Price you pay$9,802.83
- Interest at maturity$197.17
- Federal tax on the interest-$43.38
- After-tax interest$153.79
- A CD or savings account would need to pay4.25%
How it works
T-bills are sold at a discount and pay face value at maturity. The price is face value minus discount rate × days ÷ 360. The investment rate puts the return on a 365-day basis against the price you actually paid, so it's higher than the discount rate.
T-bill interest is federally taxable but exempt from state and local income tax, which makes it worth more than a CD at the same rate in high-tax states.
2026 figures: TreasuryDirect Series I rate chart.
Questions
When is the interest taxed?
In the year the bill matures. A 26-week bill bought in October is taxed in the following year.
How do I buy T-bills?
Through TreasuryDirect, or at auction through most brokerages with no fee.