If you have been waiting for a reason to revisit Series I savings bonds, the U.S. Treasury just gave you one. On May 1, 2026, the composite rate reset to 4.26%, the highest yield since the fall 2023 window that drew record buyer interest. More importantly for long-term savers, the new fixed rate is 0.90%, a floor that stays with every bond purchased through October 31, 2026, for its entire 30-year life.
That means even if inflation drops to zero in 2035 or 2040, holders are still earning 0.90% above it. In a world of variable-rate savings accounts and short-term CDs, that kind of guaranteed real return is hard to find elsewhere.
The reset marks a sharp reversal from a string of underwhelming windows. After the composite peaked at 5.27% in November 2023, yields had slipped below 4% for several consecutive periods as headline inflation cooled. A pickup in consumer prices over the past six months pushed the variable inflation component back up, delivering the strongest headline yield in more than two years.
How the 4.26% rate breaks down
Every I bond rate has two parts:
- The fixed rate (currently 0.90%) is set at purchase and never changes for the bond’s 30-year interest-bearing life.
- The inflation rate (currently 3.34% annualized) is recalculated every May and November using six months of Consumer Price Index for Urban Consumers (CPI-U) data published by the Bureau of Labor Statistics.
Treasury combines the two using an official formula that doubles the semiannual inflation reading, adds the fixed rate and a small cross-product term, then rounds to the nearest hundredth of a percent. For the current window, that math lands at 4.26%.
Here is what that looks like in practice: A saver who buys $10,000 in I bonds in June 2026 earns 4.26% annualized for the first six months, which works out to roughly $213 in interest over that period. When November 2026 arrives, the inflation half resets based on fresh CPI-U data, but the 0.90% fixed portion stays put. Interest accrues monthly and compounds semiannually, so the 4.26% figure is a current annualized rate, not a guaranteed multi-year average.
Why the fixed rate matters more than the headline
Composite rates grab attention, but the fixed rate is what separates one purchase window from another over the long haul. At 0.90%, the current fixed rate is solid by post-2008 standards, yet it trails the 1.30% offered in November 2023. That 40-basis-point gap compounds over decades. A bondholder who locked in 1.30% in late 2023 will earn more than someone buying today in every single future period, regardless of what inflation does, because both bonds share the same variable component going forward.
The higher composite rate this time around is driven almost entirely by the inflation variable, not by a more generous fixed floor. For buyers weighing whether to act now or wait, the real question is whether a future reset might offer a fixed rate above 0.90%. Treasury sets the fixed rate at the discretion of the Secretary, and it is not mechanically tied to any single benchmark. There is no published rationale for the current level, so predicting the next move is guesswork.
Still, 0.90% ranks among the better offers of the past decade. Only the November 2023 window and a handful of earlier periods have exceeded it since the program’s modern relaunch.
Where the inflation data came from
The BLS published CPI-U index values for September 2025 and March 2026, the two endpoints Treasury uses to calculate the semiannual price change feeding the inflation variable. That six-month window showed enough upward movement in consumer prices to generate a 3.34% annualized inflation adjustment, reversing the downward trend that had defined prior resets.
For context, the 3.34% annualized inflation component suggests consumer prices were rising at a pace somewhat above the Federal Reserve’s 2% target during that measurement period. Buyers earning 4.26% on their I bonds are getting a return that exceeds the inflation rate baked into the bond itself, thanks to the 0.90% fixed addition.
What happens next is genuinely uncertain. The November 2026 reset will use CPI-U data from March through September 2026, a period that has not yet concluded. Shifting trade policy and volatile energy prices add noise to any inflation forecast. Savers should treat 4.26% as a snapshot of where prices have been, not a prediction of where they are going.
How I bonds compare to other safe options
The 4.26% composite looks competitive against other low-risk alternatives available in mid-2026, but the comparison is not apples to apples.
- High-yield savings accounts at top online banks have generally been offering rates in the low-to-mid 4% range as of spring 2026, according to rate trackers like Bankrate. But those rates can drop at any time and carry no inflation adjustment. I bond rates reset every six months with CPI-U data, providing a built-in hedge.
- Certificates of deposit lock in a rate for a set term, but they lack inflation protection. A 12-month CD yielding a comparable rate might match the I bond’s current composite, yet it offers no upside if prices accelerate and no 30-year fixed floor.
- Treasury Inflation-Protected Securities (TIPS) also adjust for CPI, but they trade on the open market, meaning their prices fluctuate. I bonds never lose nominal value, making them simpler for savers who want to avoid market risk entirely.
I bonds also carry a tax advantage that savings accounts and CDs do not: interest is exempt from state and local income taxes. Federal income tax is owed on the interest, but it can be deferred until the bond is redeemed or reaches final maturity, giving holders control over when they recognize the income. And if the proceeds are used for qualified higher-education expenses, the interest may also be excluded from federal income tax, subject to income limits set by the IRS. For savers in high-tax states, the state and local exemption alone can meaningfully boost the after-tax return.
Purchase limits, lockups, and the early-redemption penalty
Each person can buy up to $10,000 in electronic I bonds per calendar year through the TreasuryDirect portal, plus an additional $5,000 in paper bonds purchased with a federal tax refund. The limit is per Social Security number, so spouses can each buy $10,000, and parents can purchase bonds in a child’s name under a separate account.
There is a hard 12-month lockup: you cannot redeem an I bond for any reason during the first year. After that, you can cash out at any time, but if you redeem before holding for five full years, you forfeit the last three months of interest as a penalty. On a $10,000 bond earning 4.26%, that penalty would amount to roughly $106 in the first year. After five years, there is no penalty at all.
Because of these constraints, I bonds work best as a complement to liquid savings, not a replacement. Money you might need within 12 months belongs in a savings account or money-market fund. Money you can set aside for at least a year, and ideally five, is where I bonds earn their keep.
What the October 31 deadline means for your purchase
Bonds purchased between now and October 31, 2026, lock in the 0.90% fixed rate permanently and earn the 4.26% composite for their first six months. After that date, the inflation variable resets, but the fixed portion does not. Waiting past October means accepting whatever fixed rate Treasury announces in November, which could be higher, lower, or the same.
For savers with room under the $10,000 electronic cap who will not need the funds within 12 months, the current window pairs a durable fixed floor with an inflation adjustment reflecting real price pressures in the economy right now. There is no way to know, based on the information Treasury has published, whether the next reset will match, beat, or undercut today’s terms. What is knowable: once you buy, that 0.90% fixed rate is yours for three decades, and no future rate change can take it away.
