I Bonds Explained: Inflation Protection for Savers

I Bond yields consist of two components added together. The fixed rate is set by the Treasury at the time of purchase and remains constant for the bond's 30-year life. The inflation rate adjusts every six months based on changes in the CPI-U (Consumer Price Index for All Urban Consumers). These two rates combine to form the composite rate that determines your actual earnings.

The Treasury announces new rates every May and November. Bonds purchased between those announcements receive the current rates for their first six-month period, then switch to the newly announced rates. For example, if you buy in March 2026, you lock in the November 2025 rates for six months, then roll to whatever rates are announced in May 2026.

Importantly, the composite rate can never go below zero. Even in a deflationary environment, you will never lose principal — the inflation component can offset the fixed rate down to zero but cannot make it negative. This principal protection, combined with the full faith and credit of the U.S. government, makes I Bonds among the safest investments available.

The Treasury limits I Bond purchases to $10,000 per person per calendar year in electronic bonds through TreasuryDirect.gov. You can buy an additional $5,000 per year in paper bonds by directing your federal tax refund using IRS Form 8888. This means a married couple filing jointly can acquire up to $30,000 in I Bonds annually — $10,000 electronic each plus $5,000 paper each.

Trust accounts, LLCs, and other entities with separate EINs can also purchase $10,000 annually, providing another avenue for those who want greater I Bond exposure. However, this requires setting up a separate TreasuryDirect account for each entity.

Electronic I Bonds can be purchased in any amount from $25 to $10,000 (to the penny), making them accessible for savers at any level. Paper bonds come in denominations of $50, $100, $200, $500, and $1,000. All purchases must be made directly through TreasuryDirect or via tax refund — I Bonds are not available through brokers or banks.

Compared to [high-yield savings accounts](/article/high-yield-savings-accounts-explained), I Bonds offer inflation-matched returns with federal tax deferral — you don't pay tax on interest until you redeem the bond. High-yield savings accounts currently offer rates around 3.5-4.0% APY with the federal funds rate at 3.64%, but those rates fluctuate as the Fed adjusts policy. I Bonds lock in inflation protection regardless of what the Fed does.

Against [CD ladders](/article/cd-laddering-strategy-explained), I Bonds provide more flexibility. While CDs lock your money for a fixed term with early withdrawal penalties, I Bonds can be redeemed after 12 months (with a 3-month interest penalty if redeemed before 5 years). After 5 years, there is no penalty at all. CDs may offer higher rates in some environments, but they carry reinvestment risk — when your CD matures, prevailing rates may be lower.

[Money market accounts](/article/money-market-accounts-vs-savings-accounts) provide the most liquidity but offer no inflation guarantee. In periods when the Fed is cutting rates, money market yields fall immediately while I Bond inflation adjustments maintain purchasing power with a lag of at most six months.

I Bond interest is exempt from state and local income taxes — only federal tax applies. This gives I Bonds an edge over savings accounts and CDs for residents of high-tax states like California and New York, where state income tax rates can exceed 10%.

Federal tax on I Bond interest can be deferred until you redeem the bond or it reaches maturity (30 years), whichever comes first. This deferral allows your full interest to compound without annual tax drag — a meaningful advantage over savings accounts where interest is taxed in the year it's earned.

For education planning, I Bonds offer an additional benefit: interest may be completely tax-free at the federal level if used to pay for qualified higher education expenses at eligible institutions. To qualify, the bond owner must be at least 24 years old at the time of purchase, and income must fall below annually adjusted thresholds. This makes I Bonds a useful supplement to 529 plans, particularly for families uncertain about whether education expenses will materialize.

I Bonds work best as a component of your safe savings allocation — the portion of your finances reserved for capital preservation rather than growth. They're ideal for the portion of an [emergency fund](/article/how-to-build-an-emergency-fund) you won't need in the next 12 months, since the one-year lock-up means they can't replace your immediate cash reserve.

For retirees or near-retirees, I Bonds provide a guaranteed real return without the interest rate risk that conventional bonds carry. When Treasury yields rise (the 10-year yield reached 4.13% in early March 2026), existing bond fund values decline — but I Bonds maintain their face value and adjust upward with inflation.

The $10,000 annual purchase limit means I Bonds cannot be your only savings vehicle for large goals. Think of them as one layer in a broader savings strategy: high-yield savings for immediate liquidity, I Bonds for inflation-protected medium-term reserves, and [diversified portfolios](/article/how-to-build-a-diversified-investment-portfolio) for long-term wealth building. Consistent annual purchases over time can build a substantial I Bond ladder with staggered redemption dates.