If you have $10,000 sitting in a savings account earning a rate your bank could cut tomorrow, the U.S. Treasury just gave you a reason to move. Series I savings bonds purchased between May 1 and October 31, 2026, will earn a composite rate of 4.26%, according to the Treasury’s official rate announcement. That is the highest I bond yield since November 2023, when the composite hit 5.27% during the tail end of the post-pandemic inflation surge.
The rate is guaranteed for your first six months of ownership, backed by the full faith and credit of the U.S. government, and your principal can never lose value. For savers weighing where to park cash they will not need for at least a year, the new rate deserves more than a passing glance.
Breaking down the 4.26% rate
Every I bond rate has two parts. The first is a fixed rate, set at 1.10% for this cycle, which stays with your bond for its entire 30-year life. Think of it as a guaranteed floor of real return above inflation. The second is a semiannual inflation rate of 1.58%, derived from changes in the Consumer Price Index for All Urban Consumers (CPI-U) published by the Bureau of Labor Statistics.
The Treasury combines both numbers using a public formula: composite = fixed rate + (2 × semiannual inflation rate) + (fixed rate × semiannual inflation rate). That math produces 4.26%.
The 1.10% fixed component is worth paying attention to on its own. For most of the 2010s, the Treasury set the fixed rate at 0.00%, meaning bondholders earned only the inflation adjustment with zero guaranteed real return above it. A fixed rate above 1% is historically generous, and it stays locked in no matter what inflation does in the years ahead.
How I bonds stack up against savings accounts and CDs
As of late May 2026, top-paying online high-yield savings accounts advertise roughly 4.0% to 4.3% APY, based on rate surveys from FDIC.gov and Bankrate. Competitive one-year CDs sit in a similar range. At first glance, the I bond rate looks like a wash. It is not, once you factor in taxes and structure.
State and local tax exemption. I bond interest is exempt from state and local income taxes. For savers in high-tax states like California or New York, a 4.26% yield with no state tax can deliver more after-tax income than a 4.3% savings account that is fully taxable at every level.
Federal tax deferral. You can defer federal taxes on I bond interest until you redeem the bond or it matures, up to 30 years out. That deferral lets interest compound without an annual tax drag, something no savings account offers.
Education tax exclusion. If you use I bond proceeds to pay for qualified higher education expenses, the interest may be entirely tax-free at the federal level, subject to income limits. The Treasury outlines the eligibility rules on its site.
Built-in inflation hedge. The 1.10% fixed rate provides a floor, and if inflation rises, your I bond rate rises with it at the next semiannual reset. A savings account rate, by contrast, can be cut by the bank at any time for any reason.
Principal protection. Unlike Treasury Inflation-Protected Securities (TIPS), which can trade below par on the secondary market, I bonds never lose principal value. Your redemption value can only go up or stay flat.
The tradeoff is liquidity. Savings accounts let you withdraw money whenever you want. I bonds lock your cash for a full 12 months, and if you redeem before five years, you forfeit the last three months of interest. On a $10,000 bond earning 4.26%, cashing out at the 12-month mark would cost you roughly $106 in forfeited interest (three months at approximately $35.50 per month).
What $10,000 actually earns
The annual purchase limit for electronic I bonds is $10,000 per person through TreasuryDirect.gov. You can buy an additional $5,000 in paper I bonds by directing part of your federal tax refund using IRS Form 8888. Married couples filing jointly can each buy $10,000 electronically, for a household total of $20,000 (plus paper bonds via refund).
If you invest the full $10,000 and the 4.26% composite holds for a full year (two six-month periods at the same rate), your bond would earn approximately $426 in interest before federal taxes. In practice, the rate will reset after your first six months of ownership based on whatever inflation component the Treasury announces in November 2026. Your 1.10% fixed rate, however, never changes.
I bonds earn interest monthly and compound semiannually. Interest is added to the bond’s principal value, so you earn interest on your interest every six months. Over long holding periods, that compounding, paired with the tax deferral, can meaningfully boost total returns compared to a taxable account earning the same nominal rate.
How to buy (and what to watch out for)
Electronic I bonds are purchased exclusively through TreasuryDirect.gov, the Treasury’s online portal. You will need a Social Security number, a U.S. address, and a checking or savings account for funding. The site’s interface is notoriously dated, but the process is straightforward: create an account, link your bank, and place your order in any amount from $25 to $10,000 (to the penny).
A few practical points worth knowing:
- The October 31 deadline is firm. Bonds purchased on or before that date lock in the 4.26% composite for their first six months. Bonds purchased starting November 1 will carry whatever new rate the Treasury sets.
- You cannot buy I bonds through a brokerage. Fidelity, Schwab, Vanguard, and other brokers do not sell them. TreasuryDirect is the only option for electronic purchases.
- Gifts count against the recipient’s annual limit. You can buy I bonds as gifts for others through TreasuryDirect, but the $10,000 annual cap applies to the recipient in the calendar year the gift is delivered, not when you purchase it. Buying a gift bond does not reduce your own $10,000 allowance.
- Trust and entity purchases have separate limits. If you have a revocable living trust, it can buy an additional $10,000 per year, effectively doubling your household capacity.
What happens after October
The November 2026 rate reset is anyone’s guess. The inflation component will depend on CPI-U data from the second half of 2026, which has not been collected yet. If consumer prices cool further, the composite rate could drop. If inflation reaccelerates due to tariffs, energy costs, or other pressures, the rate could climb.
The fixed rate is equally unpredictable. The Treasury Department sets it at its discretion and has never published a formula or detailed rationale for how it is determined. The 1.10% fixed rate could hold, rise, or fall in November with no advance signal.
For existing bondholders, the new inflation component will automatically apply to their bonds on a rolling schedule tied to each bond’s original issue month. The fixed rate locked in at purchase never changes. A bond bought in June 2026 at 1.10% fixed will always carry that 1.10% floor, even if the Treasury drops the fixed rate to 0.50% next cycle.
Who this rate works for (and who should skip it)
I bonds are not the right fit for everyone. The 12-month lockup makes them a poor choice for emergency funds you might need on short notice. The $10,000 annual cap limits their usefulness for large portfolios. And if you are in a low tax bracket in a state with no income tax, the state-tax exemption adds little value.
But for savers who can set aside money for at least a year, want a government-backed guarantee, and appreciate built-in inflation protection, the current rate is hard to dismiss. The 1.10% fixed rate means your bond will always pay at least something above inflation, even if CPI-U drops to near zero. That was not true for I bonds issued during most of the last decade, when the fixed rate sat at 0.00% and bonds paid only the inflation adjustment.
The window runs through October 31, 2026. After that, the rate resets and the current terms disappear. Where inflation, the Fed, and competing savings rates land six months from now is uncertain. What is certain today is the rate, the rules, and the deadline.
