I-Bond vs CD Laddering Comparison Calculator

How Series I Bonds Work vs CD Ladders

Series I Savings Bonds, issued by the U.S. Treasury, pay a composite rate that combines a fixed rate (set at purchase for the life of the bond) and a variable inflation rate (reset every six months based on CPI-U). Interest compounds semi-annually for up to 30 years, is exempt from state and local income tax, and federal tax is deferred until redemption (source: treasurydirect.gov). The annual purchase limit is $10,000 per Social Security number via TreasuryDirect, plus an additional $5,000 in paper bonds purchased with a federal tax refund.

A CD ladder stages CDs at staggered maturities (1, 2, 3, 4, 5 years) so one rung matures every year, providing rolling liquidity and an average yield close to the long end of the curve. CD interest is fully taxable at federal, state, and local rates in the year credited. Most CDs charge early-withdrawal penalties of 3-12 months of interest. The FDIC insures up to $250,000 per depositor per bank.

2026 Rate Environment for Safe Money

The current I-bond fixed rate, set for bonds purchased between November 2025 and April 2026, is 1.20% per Treasury data, with a composite rate around 3.98% reflecting recent CPI. CD ladder yields are tracking national averages near 4.0-4.5% for shorter rungs and 3.5-4.0% for 5-year terms per the FDIC weekly national rate survey (source: fdic.gov). When inflation runs hot, I-bonds shine; when inflation moderates, CDs often win on raw yield.

For the math here, the variable I-bond component is approximated as the annual CPI you enter, applied semi-annually. The composite rate = fixed + variable + (fixed × variable / 2). After the one-year holding restriction, I-bonds can be redeemed any time, with a 3-month interest penalty if redeemed before 5 years (source: treasurydirect.gov).

Liquidity, Lock-In, and Penalty Comparison

I-bonds are illiquid for the first 12 months — no redemption allowed at all. After that, redemption forfeits the most recent 3 months of interest if held less than 5 years. CDs vary by issuer; common penalties are 3-6 months of interest on terms under 24 months and 6-12 months on longer CDs. Some "no-penalty" CDs exist but typically pay yields 0.5-1% lower than standard CDs. For an emergency-fund or near-term-spending allocation, ladder structure or a high-yield savings account often beats either.

For broader fixed-income comparisons, see our CD laddering calculator for the full ladder structure, the I-bond Treasury rate calculator for composite-rate breakdowns, and our Treasury yield calculator for T-bill alternatives. The I-Bond vs TIPS calculator covers another inflation-hedge comparison.

When to Pick Each — A Practical Decision Framework

Pick I-bonds when: you expect inflation to run above 3% sustained, you want a state-tax-free yield, you can leave the money locked for 12+ months, and you can use the education-expense federal tax exclusion. Pick CD ladders when: you can earn 4.5%+ on shorter maturities, you want predictable cash flow from maturing rungs, your state has zero or low income tax (reducing the I-bond advantage), or you need to deploy more than $10,000-$15,000 per year (the I-bond limit).

Last updated April 2026. Sources: treasurydirect.gov, fdic.gov, irs.gov.