T-Bill vs. CD Calculator: After-Tax Comparison
Treasury bill interest is taxed federally but not by your state; CD interest is taxed by both. Enter your tax rates to see which one leaves you with more. The T-bill yield defaults to today's Treasury yield for the term.
The T-bill wins
After tax, the CD keeps $157.08 and the T-bill keeps $169.75 over 6 months.
With your tax rates, a CD needs at least 4.70% APY to match a 4.40% T-bill.
Default T-bill yield: U.S. Treasury daily par yield curve, 2026-10-21, converted to APY.
Today's best 6 months CD rates
- Popular Direct 4.35% 6 months
- Flagstar Bank 4.10% 6 months
- Huntington Bank 4.10% 5 months, Chicago, IL
- Valley Bank 4.10% 6 months
- Barclays 4.00% 6 months
From the institutions we track, verified daily. See all rates.
Why taxes change the answer
CD after tax = interest × (1 − federal − state) and T-bill after tax = interest × (1 − federal). In a state with a 5% income tax and a 22% federal bracket, a 4.50% T-bill matches a CD paying about 4.81%.
Questions
Are T-bills exempt from state tax?
Yes. Interest on Treasury bills, notes and bonds is exempt from state and local income tax, but taxed federally.
Are T-bills safer than CDs?
Both are very safe. T-bills are backed by the U.S. government; CDs at FDIC or NCUA institutions are insured up to $250,000 per depositor, per ownership category.