Series I savings bonds occupy an unusual corner of the savings world: they are backed by the U.S. Treasury, adjust with inflation twice a year, and let an owner postpone federal tax on the interest for decades. For bonds bought between May and October 2026, the combined rate is 4.26 percent, and the interest is exempt from state and local tax on top of the federal deferral. For a retiree looking to protect a slice of cash from rising prices without taking on market risk, that mix of features is worth understanding before the next rate reset.
How the inflation-linked rate actually works
An I bond’s return has two parts that combine into what the Treasury calls the composite rate. A fixed rate stays the same for the entire life of the bond, while an inflation rate resets every six months to track the Consumer Price Index. For bonds issued from May through October 2026, TreasuryDirect set the composite rate at 4.26 percent, made up of a 0.90 percent fixed rate and a 3.34 percent annualized inflation component. Because the fixed portion is locked in at purchase, buying while it is above zero means every future inflation adjustment stacks on top of a permanent floor.
The Treasury announces new rates on the first business day of May and November, so the inflation piece on any given bond changes on a rolling six-month schedule tied to its own issue month. Interest accrues monthly and compounds semiannually, and the rate an owner earns is the composite figure in effect for each of those six-month windows rather than a single fixed yield for the life of the bond.
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The tax treatment that sets I bonds apart
The tax rules are where I bonds diverge sharply from a bank account. Interest earned on the Series I savings bond is entirely exempt from state and local income tax, a meaningful edge for someone living in a high-tax state. At the federal level, the owner can defer reporting the interest until the bond is cashed or reaches final maturity at 30 years, rather than paying tax on the growth year by year.
That deferral gives the holder control over timing. Interest can be pushed into a year when income — and therefore the tax rate — is expected to be lower, such as after a person stops working. There is also a separate education provision that can make the interest fully tax-free when proceeds are used for qualifying tuition and fees and the owner meets income limits, though that break carries its own eligibility rules and is not automatic.
For an older saver, the combination matters because taxable interest can quietly raise other costs. Since bond interest is deferred rather than reported annually, it does not inflate a retiree’s taxable income each year the way a certificate of deposit’s interest does — which can help in years when a higher income figure would push up the portion of Social Security that is taxed or trigger a Medicare premium surcharge.
The trade-offs and purchase limits to weigh
I bonds are built for patience, not for quick access. A bond cannot be redeemed at all during its first 12 months, and cashing one before five years costs the most recent three months of interest as a penalty. After five years, a bond can be redeemed with no penalty at any time up to the 30-year mark. Those rules make an I bond a poor substitute for an emergency fund but a sensible home for money that will not be needed soon.
Purchases are capped, too. An individual can buy up to $10,000 in electronic I bonds per calendar year through a TreasuryDirect account, which limits how large a position a single person can build in any one year. Bonds are bought directly from the Treasury rather than through a brokerage, and they are registered to a specific owner, with the option to name a beneficiary.
The bigger picture is that an I bond is a hedge, not a growth engine. Its purpose is to keep a portion of cash from losing purchasing power when inflation runs hot, with the government’s backing removing default risk and the tax features improving the after-tax return. For a retiree deciding where to hold money that must stay safe but should not simply erode, checking the current composite rate against the alternatives — and doing so before the next May or November reset — is the practical first move.
Why an I bond’s value never falls
A feature that sets the I bond apart from other inflation-linked investments is its built-in floor. The composite rate is calculated from the fixed rate plus twice the semiannual inflation rate plus a small combined term, but the Treasury will not let the result drop below zero. Even in a stretch of falling prices, when the inflation component turns negative, the worst an I bond can do is earn nothing for that six-month window — its redemption value never declines. That guarantee is why the bond’s principal is considered untouchable in a way that a Treasury Inflation-Protected Security, whose principal can fall with deflation, is not.
The two-part structure also rewards timing the fixed rate rather than the headline number. Because the 0.90 percent fixed rate rides with the bond for all 30 years, a bond bought while the fixed rate is positive keeps that permanent advantage over every bond issued in months when the fixed rate was zero, regardless of how the inflation piece moves later. When the inflation rate resets on the bond’s own six-month anniversary, that fixed floor stays put — so two bonds bought a year apart can pay noticeably different composite rates for their entire lives.
This article was researched and drafted with the assistance of AI and reviewed by The Money Overview editorial team.
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