I-Bond Fixed Rate Calculator 2027
I-Bonds combine a fixed rate (locked at purchase) + semi-annual inflation rate. The 2026 H1 fixed rate of 1.30% is the highest since 2007 — locking it before reset is meaningful. This tool computes composite yield and 10-year projected return.
How I-Bond Rates Work
Composite rate = fixed rate + (2 × semi-annual inflation rate) + (fixed × 2 × inflation). Fixed rate locked at purchase for full 30-year life. Inflation rate resets every 6 months (May and November) based on CPI-U. Earnings credited monthly, compounded semi-annually.
Why Fixed Rate Matters Long-Term
Variable inflation component fluctuates; fixed rate is the floor. 2007: 1.40% fixed (highest ever). 2010-2022: 0.00%-0.30% fixed. 2026 H1: 1.30% fixed — second-highest in 20 years. Lock as much as possible before next reset if fixed stays attractive. Annual purchase limit: $10K per SSN + $5K via paper bonds from tax refund.
Rules and Strategy
One-year holding minimum (cannot sell). 5-year holding required to avoid 3-month interest penalty. Federal tax deferred until redemption — useful for tax-bracket management. State tax exempt. Possible Section 135 education exclusion if used for qualified higher education. Pairs well with tax-deferred accounts in income-distribution strategy.
Source: Treasury Direct, IRS Section 135 (Education Bond Exclusion), Bureau of Labor Statistics CPI. Last updated: May 2026.