Key Takeaways
- Low-risk U.S. Treasury bond with inflation protection.
- Interest = fixed rate + inflation rate, adjusts semiannually.
- Minimum $25 purchase; $10,000 max per year electronically.
- Redeem after 1 year; penalty if cashed before 5 years.
What is Series I Bond?
Series I Bonds are U.S. Treasury securities designed to protect your savings from inflation by combining a fixed interest rate with a variable inflation rate that adjusts every six months. These bonds are backed by the full faith and credit of the U.S. government, making them a popular safe haven investment during uncertain economic times.
Purchases are made electronically through TreasuryDirect, with a minimum investment of $25 and an annual limit of $10,000 per individual.
Key Characteristics
Series I Bonds offer unique features that set them apart from other government securities:
- Inflation Adjustment: The interest rate includes a variable component tied to the Consumer Price Index for All Urban Consumers (CPI-U), protecting your purchasing power.
- Fixed Rate: Set at purchase and remains constant for the bond’s 30-year term, ensuring a baseline return regardless of inflation changes.
- Tax Advantages: Interest earned is exempt from state and local taxes and can be deferred federally until redemption or maturity.
- Liquidity: Must be held at least one year, with a penalty of forfeiting the last three months’ interest if redeemed before five years.
- Purchase Limits: Maximum $10,000 annually per person via TreasuryDirect, with a $25 minimum.
- Interest Compounding: Interest compounds semiannually, increasing the principal value on which future interest is calculated.
How It Works
Series I Bonds earn interest through a composite rate combining the fixed rate and an inflation rate that is updated twice yearly based on the CPI-U. This dual-rate system means your bond’s value adjusts with economic conditions, helping maintain real returns even during periods of rising prices.
Interest accrues monthly and compounds every six months, growing your investment without requiring reinvestment. The bond matures after 30 years, but you can redeem it any time after one year, subject to penalties if under five years.
For investors interested in bond strategies, understanding the inflation-adjusted rate component is crucial. Comparing Series I Bonds with other fixed income options like those highlighted in best bond ETFs can help diversify your portfolio effectively.
Examples and Use Cases
Series I Bonds suit investors seeking preservation of capital with protection against inflation. Here are typical scenarios where they are beneficial:
- Conservative Investors: Those who prioritize low-risk investments with government backing over higher volatility stocks.
- Education Savings: Parents or students aiming to save for tuition may take advantage of tax benefits if used for qualified higher education expenses.
- Inflation Hedging: During periods of rising prices, I Bonds outperform traditional savings accounts, complementing holdings in stocks like Delta or American Airlines, which may face inflation-related operating cost increases.
- Portfolio Diversification: Combining I Bonds with low-cost funds such as those outlined in best low-cost index funds supports a balanced investment approach.
Important Considerations
While Series I Bonds offer attractive inflation protection and government backing, they come with limitations. The one-year minimum holding period restricts immediate liquidity, and early redemption before five years results in a three-month interest penalty.
Also, the fixed rate portion can be low if purchased during periods of high inflation, potentially limiting long-term returns compared to equities. Evaluating your individual goals with awareness of macroeconomic trends, such as those discussed in macroeconomics, will help determine if I Bonds fit your portfolio strategy.
Final Words
Series I Bonds offer a reliable way to protect your savings from inflation with a government-backed guarantee and semiannual compounding. Consider purchasing before the next inflation rate update to lock in today’s composite rate and maximize your returns.
Frequently Asked Questions
A Series I Bond is a low-risk U.S. Treasury security that offers inflation protection by combining a fixed interest rate with a variable inflation rate that adjusts every six months to preserve purchasing power.
Series I Bonds earn interest monthly, which compounds semiannually by adding accrued interest to the principal. This means your investment grows as new interest is calculated on an increasing balance.
You can buy Series I Bonds electronically starting at $25, with an annual purchase limit of $10,000 per person through TreasuryDirect.gov.
You must hold a Series I Bond for at least one year before redeeming. If you cash it out before five years, you forfeit the last three months of interest as a penalty.
The interest rate on Series I Bonds is a composite of a fixed rate set at purchase plus a semiannual inflation rate based on changes in the Consumer Price Index, ensuring your returns keep pace with inflation.
Yes, Series I Bonds are backed by the full faith and credit of the U.S. government, making them very low-risk investments with protection against inflation.
No, Series I Bonds are currently only available for purchase electronically through TreasuryDirect.gov; paper versions are no longer issued.
If inflation drops or becomes negative, the inflation component of the Series I Bond rate can decrease, but the overall composite rate will never go below zero, so you won't lose principal.

