A Series I savings bond splits its interest into two separate pieces, and only one of them ever changes. The fixed-rate half is locked in on the day the bond is bought and stays exactly the same for the bond’s entire 30-year life, while the inflation half resets every six months to track the actual cost of living. A saver who buys when the fixed rate is high keeps that premium above inflation for decades, even after rates for new buyers fall.
Two Rates in One Bond, and Only One Ever Locks
TreasuryDirect describes an I bond’s return as a composite rate made up of a fixed rate and an inflation rate, combined twice a year into a single earnings rate applied to the bond’s growing balance. The fixed rate is set once, at purchase, and never changes for as long as that specific bond is held, while the inflation component is recalculated every May 1 and November 1 based on the Consumer Price Index and applied uniformly to every I bond outstanding, regardless of when each one was originally bought.
Treasury set the fixed rate for I bonds issued between May 1, 2026, and October 31, 2026, at 0.90%, combined with a 3.34% annualized inflation rate for a 4.26% composite rate over that six-month stretch. Anyone who buys during this window locks in that 0.90% fixed rate for up to 30 years, even though the inflation piece riding alongside it will keep changing every six months for as long as the bond is held.
Interest on an I bond is exempt from state and local income tax and, like an EE bond, is subject to federal tax generally in the year it is cashed or reaches final maturity at 30 years, unless the owner elects to report it annually. A person can buy up to $10,000 in electronic I bonds per calendar year through TreasuryDirect, a separate limit from the one that applies to EE bonds, so a saver can hold both types at once without either purchase counting against the other’s cap.
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Why the Fixed Rate Is the Part Worth Watching
The inflation component protects a bond’s purchasing power no matter when it was bought, since every I bond in existence gets the same new inflation rate on the same reset dates, but it doesn’t make one bond a better deal than another. The fixed rate is what separates a strong I bond purchase from a mediocre one, because the fixed rate that applies at the time of purchase never changes for the life of that bond, so two people who bought I bonds years apart can be earning very different total returns today even though both are riding the same current inflation adjustment.
A saver who bought an I bond when the fixed rate briefly touched 3.4% in 2000, or even the 1.30% offered in late 2023, locked in real interest well above what today’s 0.90% fixed rate provides, and keeps that edge for the full life of the bond regardless of how rates move for new buyers afterward. That is the practical meaning of “locking in real interest for years”: the fixed-rate half of an I bond is a one-time decision that keeps paying off, or underpaying, for decades after the purchase.
What This Means for Money Bought Today
Buying an I bond today locks in the current 0.90% fixed rate for as long as that bond is held, which is a modest premium over inflation compared with some past rate-setting periods but still guarantees the bond’s purchasing power never erodes, since the inflation component adjusts every six months to match actual price changes. A saver who buys now and later sees the fixed rate rise for new buyers doesn’t get to switch; the higher rate applies only to bonds purchased in that later window.
That makes timing matter more for an I bond than for many other savings vehicles: the inflation protection is available to any buyer at any time, but the fixed-rate premium above inflation is fixed the moment the purchase is made and never revisited again. Treasury announces the next fixed and inflation rates on November 1, 2026, and a saver deciding when to buy is really deciding how much of a bet to place on that one number rather than on the inflation adjustment, which every I bond receives regardless of purchase date.
For an older saver weighing an I bond against a Series EE bond or a bank CD, the I bond’s advantage is that its return can never fall behind inflation the way a fixed-rate CD’s return can during a period of rising prices, while its disadvantage is that the composite rate can also drop sharply if inflation cools, unlike an EE bond’s guaranteed doubling over 20 years. Choosing between the two often comes down to whether the priority is protection against inflation or a guaranteed floor on total return.
This article was produced with the assistance of AI and reviewed by The Money Overview editorial team before publication.
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