I Bond Treasury Rate Calculator

Calculate the composite yield of a U.S. Series I Savings Bond. The Treasury Department combines a fixed rate that lasts the bond's life with an inflation rate that resets every 6 months.

Max $10,000 per person per year (electronic)
Set at purchase, locked for 30 years (May 2025-Oct 2025: 1.10%)
Resets every May 1 and Nov 1 based on CPI-U
Fed long-term target: 2.0%

Year-by-Year Projection

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How Series I Savings Bonds Work

Series I Savings Bonds are inflation-protected U.S. government savings bonds. The Treasury Department combines two rates to determine your yield: a fixed rate that stays the same for the entire 30-year life of the bond, and an inflation rate that resets every 6 months on May 1 and November 1 based on the Consumer Price Index for All Urban Consumers (CPI-U). The composite rate formula is: Composite = Fixed + (2 × Inflation) + (Fixed × Inflation), with a 0% floor on the composite rate (source: TreasuryDirect.gov).

2026 I Bond Rate History and Outlook

I Bonds reached a peak composite rate of 9.62% in May 2022 due to high inflation, dropping to roughly 4.0-5.3% in 2024 as inflation cooled. The November 2024 issue had a 1.20% fixed rate plus 2.96% inflation rate, for a composite of 5.20%. The May 2025 fixed rate dropped to 1.10%. As of early 2026, fixed rates remain in the 1.0-1.2% range with composite rates around 4.0-4.5% depending on issue date. The fixed rate is the most valuable component because it persists for 30 years — locking in a 1.20% real return is historically attractive when 5-year TIPS yield 1.5-2.0%.

I Bond Tax Advantages

I Bonds enjoy three tax breaks. First, federal tax deferral: you don't pay taxes on accrued interest until you redeem the bond (or it matures at 30 years). Second, no state or local income tax — significant for residents of California, New York, New Jersey, Oregon, Hawaii, and other high-tax states. Third, the Education Tax Exclusion: if you use I Bond proceeds to pay qualified education expenses for yourself, your spouse, or your dependent, the interest may be entirely tax-free, subject to income phaseouts ($104,400-$134,400 single, $156,800-$186,800 MFJ for 2026). This makes I Bonds particularly powerful for college savings (source: IRS Publication 550).

I Bond Limits and Redemption Rules

Each individual can purchase $10,000 in electronic I Bonds per calendar year through TreasuryDirect, plus up to $5,000 in paper I Bonds purchased with federal tax refund money. Married couples and businesses with separate EINs can effectively double or triple this limit. You cannot redeem an I Bond in the first 12 months. Redeeming between months 12-60 forfeits the most recent 3 months of interest. After 5 years, redemption is penalty-free. Bonds stop earning interest after 30 years. Strategy: even if you plan to hold long-term, don't put more than 10% of liquid assets into I Bonds because of the 1-year lockout. Last updated: April 2026.