Important Educational Disclaimer
This article is for educational and informational purposes only and does not constitute financial, tax, or investment advice. Series I Savings Bonds (I-bonds) are issued by the US Treasury Department and tax treatment varies by individual circumstance and state of residence. Rates and rules current as of May 20, 2026. The Savvy Investor Guide is an educational resource operated by The Savvy Investor Limited (UK Company No. 14816921) and does not provide regulated financial advice in the United States or the United Kingdom. Before making any investment decision, consult a qualified registered investment adviser, tax professional, or financial planner.
The US Treasury raised the Series I Savings Bond composite rate to 4.26% for the May-October 2026 window, effective May 1, 2026. The fixed-rate component held at 0.90%, unchanged from November 2025. For the first time in several years, the headline US I-bond rate sits above 4%, and it now compares favorably to top high-yield savings accounts and one-year CDs once tax treatment is factored in. This is the same week the UK’s National Savings & Investments raised the Premium Bonds prize fund rate to 3.8% from the July draw onward. Two countries, two state-backed savings programs, materially different mechanics. Here is the US picture.
In short
- I-bond composite rate: 4.26% annualized for the May 1 to October 31, 2026 window, up from 4.03% in the prior window.
- Fixed-rate component: 0.90%, unchanged from November 2025. This 0.90% is guaranteed for the bond’s 30-year life and is the part of the rate that distinguishes I-bonds from a pure inflation-linked instrument.
- Inflation/variable component: 3.36%, derived from CPI-U rising 1.67% over the six months to March 2026.
- Series EE Savings Bonds: 2.40% (unchanged); guaranteed to double in value if held 20 years.
- Annual purchase limit: $10,000 per person via TreasuryDirect, plus an additional $5,000 in paper bonds purchased using federal tax refund proceeds (Form 8888).
- Lock-in period: 12 months minimum holding. Bonds cannot be redeemed before 12 months from purchase.
- Early redemption penalty: 3 months of interest if redeemed within 5 years of purchase. No penalty after 5 years.
- Tax treatment: federal income tax deferred until redemption (or final maturity at 30 years); fully exempt from state and local income tax. Qualified education redemption may exempt the interest from federal tax entirely.
- For a saver in a higher federal tax bracket and a high state income tax state (California, New York, Massachusetts), the after-tax real return on I-bonds materially beats most taxable HYSAs and CDs at comparable headline rates.
- Cross-Atlantic comparison: US I-bonds 4.26% composite (with 0.90% fixed guaranteed life); UK Premium Bonds 3.8% prize fund rate from July, tax-free as prize income but probabilistic in payout for most holders.
Market context, week ending 22 May 2026: US Treasury yields hit multi-decade highs in the days before this article published. The 30-year Treasury briefly touched 5.197% on 20 May (the highest level since July 2007); the 10-year sat near 4.60%; Freddie Mac’s 30-year fixed mortgage rate jumped 15 basis points to 6.51% on 21 May. The drivers, according to bond market analysts, were Moody’s downgrade overhang on US sovereign debt, fiscal deficit concerns around the One Big Beautiful Bill Act provisions, and an Iran-linked energy risk premium. A partial easing came late in the week from US-Iran peace-agreement signals. Against that backdrop, a US-Treasury-backed savings bond at a 4.26% composite rate with full inflation protection is a more interesting proposition than it would have been six months ago, particularly for the cash bucket of a portfolio that would otherwise sit in money market funds or short-dated Treasury bills.
What the Treasury announced on May 1
TreasuryDirect confirmed on May 1, 2026 that the new Series I Savings Bond rates would apply for the six-month window beginning that day. The composite rate of 4.26% reflects the standard I-bond formula, which combines a fixed rate (set when the bond is issued and held constant for the bond’s 30-year life) with a variable rate (reset every six months based on CPI-U).
The fixed-rate component of 0.90% means that any I-bond purchased between May 1 and October 31, 2026 will earn 0.90% above the inflation rate for the next 30 years, regardless of how the variable rate moves. This is a structural improvement on holding pure cash, where every dollar of return is fully exposed to inflation erosion. For savers thinking in real-return terms, the 0.90% fixed is the part of the I-bond rate worth focusing on.
The variable component of 3.36% reflects CPI-U inflation of 1.67% over the six months from October 2025 to March 2026 (the data window the Treasury uses for the May reset). The variable rate is annualized for presentation: 1.67% over six months annualizes to 3.36%. If inflation runs higher in the April-September 2026 window that feeds into the November 2026 reset, the variable component will rise; if inflation softens, it will fall.
I-bonds purchased today therefore earn 4.26% for the first six months. On the bond’s 6-month rate-reset anniversary, the variable rate will be replaced with the variable rate then in force, while the 0.90% fixed continues for the bond’s life.
How I-bonds compare to other safe-money options in May 2026
For US savers building cash positions for emergency funds, near-term goals, or inflation-protection allocations, I-bonds are one of several options. Here is the comparable yield table as of mid-May 2026.
I-bonds vs high-yield savings accounts
Top high-yield savings accounts (HYSAs) are paying around 4.5% to 4.7% APY at the top of the market (Marcus, SoFi, Ally, Wealthfront, and several online banks). On the headline rate, that beats I-bonds at 4.26%. The arithmetic shifts once tax is factored in.
HYSA interest is taxed as ordinary income at federal, state, and local levels. For a saver in the 24% federal bracket living in California (where state income tax can reach 9.3% on this income), a 4.6% HYSA delivers approximately 3.08% after tax. The same saver holding I-bonds at 4.26% earns 4.26% with no current tax (federal deferred, state and local exempt). The after-tax yield gap reverses by roughly 1.2 percentage points in favor of I-bonds.
For a saver in a no-state-tax state (Texas, Florida, Tennessee, Nevada, etc.), the gap narrows substantially. A 4.6% HYSA delivers approximately 3.50% after the federal 24% bite; I-bonds at 4.26% deliver 4.26% deferred. The I-bond advantage persists but is smaller.
The other HYSA factor is liquidity. HYSA balances are accessible same-day or next-day with no penalty. I-bonds are locked for 12 months absolutely, and any redemption between 12 months and 5 years costs 3 months of interest. For genuine emergency funds, HYSAs are the cleaner instrument. For inflation-protection allocations or savings with a 1-5 year horizon, I-bonds are usually the better trade.
I-bonds vs 1-year CDs
Top 1-year certificates of deposit are paying around 4.6% APY in mid-May 2026 (BMO Alto, Bread Financial, Marcus, and several credit unions). 1-year CDs lock the rate for the term, so the headline rate advantage over I-bonds is roughly 30 basis points before tax.
The tax math is similar to HYSAs but worse for the saver. CD interest is reported in the year it accrues even though it may not be paid until maturity (constructive receipt). I-bond interest is fully deferred until redemption. For a saver in a higher federal bracket buying CDs and rolling them at maturity, the year-by-year tax drag compounds. I-bonds compound interest tax-deferred, which produces a meaningfully higher 5-year terminal value for the same nominal yield assumption.
I-bonds vs Treasury bills
1-year Treasury bills sit around 4.4-4.6% on the auction yield in mid-May 2026, and 3-month T-bills are paying around 4.5-4.6%. T-bill interest is taxed federally but is exempt from state and local tax, like I-bonds. The headline rate advantage of T-bills over I-bonds is around 10-30 basis points.
The structural difference is that T-bills mature at a fixed date and the proceeds are taxed when the bill matures, while I-bond interest is deferred until redemption (potentially indefinitely, up to the 30-year final maturity). For savers who want predictable income each year, T-bills give a clean tax event. For savers who want to defer the tax until a strategic redemption year (early retirement, a lower-income year), I-bonds offer a planning lever T-bills do not.
I-bonds vs TIPS
Treasury Inflation-Protected Securities (TIPS) are the other inflation-linked Treasury option. TIPS adjust their principal in line with CPI-U and pay a fixed coupon on the adjusted principal. The 10-year TIPS yield in mid-May 2026 is around 2.0-2.3% real (i.e. 2.0-2.3% plus the headline inflation rate). That real-yield headline is more than double the I-bond fixed component of 0.90%, which sounds like a TIPS advantage.
The structural differences matter. TIPS held in a taxable account generate annual “phantom income” because the inflation-adjusted principal increase is taxable each year even though the cash payment happens at maturity. TIPS pay coupon income annually that is taxed annually. I-bonds defer everything to redemption. TIPS are typically held in tax-advantaged accounts (IRAs, 401(k)s) to neutralize the phantom-income problem; I-bonds are typically held in a taxable account precisely because their tax treatment is unusually favorable in a taxable wrapper.
For an investor with retirement-account space available, TIPS are usually the cleaner long-term inflation hedge at the current 2%+ real yield. For an investor with all taxable money or an investor specifically wanting state-tax-free interest, I-bonds at 4.26% composite are competitive in a way they have not been at any point since 2022.
The UK comparison: Premium Bonds at 3.8% from July
UK readers will recognize that the UK’s National Savings & Investments raised the Premium Bonds prize fund rate to 3.8% effective from the July 2026 prize draw. Both products are state-backed (US Treasury and HM Treasury respectively), both are popular retail savings vehicles, and both received a rate increase in May 2026. Beyond that, the comparison breaks down.
UK Premium Bonds pay a tax-free “prize” rather than guaranteed interest. The 3.8% rate is an average across all bondholders; for an individual saver, actual return depends on luck and on how many bonds are held. A £50,000 holding (the UK maximum) typically clusters around the prize fund rate over time; a £1,000 holding typically earns well below it. The product is more like a lottery wrapper for cash than an interest-bearing account.
US I-bonds pay guaranteed interest of 4.26% for the first six months on every dollar invested. The fixed-rate component of 0.90% is guaranteed for 30 years. The product is a Treasury-backed savings bond, not a lottery. For an investor optimizing for predictable return and tax efficiency, I-bonds are the cleaner instrument. For the UK investor who values the lottery-adjacent character of Premium Bonds or who has exhausted ISA allowance, Premium Bonds remain a defensible product at the new rate. See our Premium Bonds rise to 3.8% piece for the UK detail.
Who I-bonds at 4.26% genuinely suit
Three groups of US savers have a strong case for I-bonds at the current rate.
1. Higher-bracket federal taxpayers in high-state-tax states
The single largest beneficiary of I-bonds at the current rate is a saver in the 32% or 37% federal bracket living in California (top state rate 13.3%), New York (top state and city rate 10.9% plus NYC), Massachusetts (top rate 9.0%), or Oregon (top rate 9.9%). For these savers, the combined federal-plus-state tax bite on a comparable taxable HYSA or CD can exceed 45%. The I-bond exemption from state and local tax plus federal deferral produces a real after-tax yield that is materially better than nominally similar taxable instruments.
For a 37% federal bracket saver in California holding $10,000 in I-bonds for 5 years at the current rate, the rough after-tax yield differential vs a 4.6% HYSA is approximately 1.4 percentage points per year, or roughly $700 in cumulative real value over the 5-year window.
2. Savers building a 1-to-5-year goal fund
For savings earmarked for a goal 1 to 5 years out (a down payment, a wedding, a planned career break), I-bonds are a strong fit. The 12-month minimum lock-in is rarely binding on this timeline. The 3-month interest penalty for redemption between 12 months and 5 years is small relative to the inflation protection and tax deferral over the same window. The 5-year completion point removes the penalty entirely.
For a couple saving for a 2027 down payment, holding $20,000 ($10k each) in I-bonds in 2026 and 2027 ($40,000 total over two years) provides Treasury-backed safety, inflation protection, state-tax-free interest, and a predictable maturity profile. The same money in an HYSA would lose real value year by year at any inflation rate above the HYSA’s after-tax yield.
3. Savers who want a structural inflation hedge in a taxable account
If TIPS in a taxable account would trigger annual phantom-income tax pain, and a retirement account is already maxed out, I-bonds are the cleanest available inflation-linked instrument for a taxable holder. The 0.90% fixed-rate floor guarantees a positive real return for the bond’s life. The variable-rate component tracks CPI-U, so principal does not erode in real terms. The tax deferral converts the holding into a flexible-redemption-year planning tool.
Who is better off elsewhere
Three groups have a weaker case for I-bonds at 4.26%.
- Savers in no-state-tax states with money in tax-deferred wrappers. If you live in Texas, Florida, Tennessee, Nevada, South Dakota, Wyoming, Alaska, Washington, or New Hampshire (which taxes interest at 0% as of 2025 reforms), the state-tax-free feature of I-bonds delivers no extra benefit. If you have room in an IRA or 401(k), the same money there in a TIPS fund or short-duration Treasury fund may produce a higher after-tax outcome.
- Emergency-fund holders who need same-day liquidity. I-bonds cannot be touched for 12 months. For emergency cash that may be needed tomorrow, a top HYSA at 4.5%+ is the right answer despite the lower headline rate.
- Investors with a multi-decade horizon and risk capacity. The 4.26% composite is competitive with cash alternatives but is well below the long-run expected return of a diversified stock-and-bond portfolio. For a 30-year horizon, the I-bond fixed rate of 0.90% real is unlikely to compete with broad equity index returns. I-bonds work as a cash-and-emergency-money instrument and as a near-term-goals vehicle, not as a long-run accumulation strategy.
Practical mechanics: buying, holding, redeeming
Buying I-bonds
Two routes are available.
Electronic I-bonds via TreasuryDirect. Open an account at treasurydirect.gov. Account opening requires a Social Security number, a US bank account for funding, and an identity verification step. The minimum purchase is $25 and the maximum per person per year is $10,000. Purchases are made via bank transfer from your linked checking or savings account. Bonds are credited to your TreasuryDirect account within 1-2 business days.
Paper I-bonds via federal tax refund. When filing your federal tax return, complete Form 8888 to direct up to $5,000 of your refund into paper I-bonds. This is the only way to obtain paper bonds and the only way to exceed the $10,000 electronic annual limit (combined with the electronic purchase, total annual I-bond exposure can reach $15,000 per person per year). Paper bonds are mailed to your home address.
The annual limits are per Social Security number. A married couple can each purchase $10,000 electronically plus $5,000 in paper bonds via a joint tax refund, giving a household maximum of approximately $25,000 per year. Trust accounts and certain business entities can also purchase I-bonds, expanding the household limit for those with appropriate structures.
Holding I-bonds
Bonds earn interest from the first day of the month in which they are purchased. Interest is added to the bond’s value monthly and compounds semi-annually. The current rate (4.26% composite) applies for the first six months of the bond’s life; on the 6-month anniversary, the variable rate component is replaced by the variable rate then in force, while the 0.90% fixed continues.
No annual statements or tax forms are issued while the bond is held. Interest accrues to the bond’s value but is not reported to the IRS or to state tax authorities until the bond is redeemed.
Redeeming I-bonds
Electronic I-bonds can be redeemed online via TreasuryDirect after the 12-month minimum holding period. Proceeds typically arrive in the linked bank account within 1-2 business days. If redeemed within 5 years of purchase, the last 3 months of interest is forfeited as a penalty.
Paper bonds can be redeemed at most banks for amounts under $1,000, or via TreasuryDirect after converting the paper bond to electronic.
At redemption, the accrued interest is reported on Form 1099-INT for federal income tax purposes. State and local tax does not apply. The bond holder can elect annual interest reporting instead of deferral when the bond is purchased (rarely advantageous for most savers, but available).
Final maturity
I-bonds stop earning interest at 30 years from the issue date. The bond must be redeemed within that window or the principal-plus-accrued-interest sits idle without earning further return.
FAQ
How does the rate reset work?
I-bonds have two rate components: a fixed rate set at purchase (held for the bond’s 30-year life), and a variable inflation rate reset every six months based on CPI-U. The composite rate combines both. For a bond purchased in May 2026, the first 6 months pay 4.26%. After that, the variable component is replaced with whatever the variable rate is on the 6-month anniversary, while the fixed rate remains 0.90%.
Should I buy in May 2026 or wait for the November reset?
The May 2026 fixed rate of 0.90% is the same as November 2025. If you buy now, you lock in that 0.90% for 30 years. The November 2026 reset could see the fixed rate rise (Treasury sets it based on TIPS yields and historical patterns) or fall. There is no way to predict the next fixed rate change. Waiting risks a lower fixed rate at the next reset; buying now risks missing a higher fixed rate. For most savers, buying when the maths works today is the more defensible choice.
Can I avoid federal tax on I-bond interest entirely?
Possibly, via the qualified education exclusion. If I-bonds are redeemed in the same calendar year that the holder pays qualified higher-education expenses (tuition and required fees, with some restrictions), the interest may be excluded from federal tax. Income phase-out limits apply ($96,800 single / $145,200 married filing jointly for 2026; partial exclusion above that to $111,800 / $175,200). The exclusion applies only to the holder, not to bonds gifted to children. This is a narrow but valuable strategy for parents and savers within the income bands.
What if I need the money before 12 months are up?
You cannot redeem I-bonds before the 12-month minimum holding period under any circumstances except disaster-area provisions in specific declared disasters. For money you may need in under 12 months, use a high-yield savings account or a short-term Treasury bill instead.
Are I-bonds protected by FDIC insurance?
I-bonds are not FDIC-insured because they are direct obligations of the US Treasury. They are backed by the full faith and credit of the United States government, which is structurally a stronger backing than FDIC insurance (FDIC covers $250,000 per depositor per insured bank; Treasury backing has no dollar cap and applies to the entire bond principal-plus-interest).
Can a trust or LLC buy I-bonds to exceed the $10,000 limit?
Trusts can purchase I-bonds via TreasuryDirect with their own $10,000 annual limit, separate from the grantor’s personal limit. LLCs can purchase via an entity TreasuryDirect account. These structures can materially expand the household maximum, but they require specific account setup and ongoing compliance. The savings need to justify the administrative overhead.
The Savvy Investor’s take
I-bonds at 4.26% composite with a 0.90% fixed-rate floor are competitive with HYSAs, CDs, and short-term Treasuries on a pre-tax headline basis, and they win on an after-tax basis for almost any saver in a higher federal bracket living in a state with meaningful income tax. The 30-year fixed-rate guarantee of 0.90% real return is the structural feature that distinguishes I-bonds from every alternative cash-substitute instrument. That floor is the part of the rate worth paying attention to, not the headline composite which will reset every six months.
For savers who already hold the typical $10,000 maximum per year, the May 2026 announcement is a reason to add the next allocation when the 2026 calendar year starts (or to bring forward 2026 purchases that have not yet been made). For savers new to I-bonds, opening a TreasuryDirect account and making a first purchase before the October 31, 2026 window closes is the simplest way to lock in the 0.90% fixed for life. The November 2026 fixed rate could be higher, lower, or unchanged. Acting on the rate you can see is the more defensible approach.
The cross-Atlantic context is interesting. The same week that US savers got a 23 basis-point rise in the I-bond composite, UK savers got a 50 basis-point rise in the Premium Bonds prize fund rate. Both Treasury-backed. Neither would deliver a portfolio’s worth of long-term return, but both have a place in the cash-and-near-term-goals portion of a balanced personal finance plan. For SIG readers in both countries, the products are not substitutes; they are jurisdiction-specific instruments serving similar roles in their respective tax systems. The structural advantages of I-bonds in a US taxable account, and of Premium Bonds for higher-rate UK taxpayers who have used their Personal Savings Allowance and ISA allowance, are the cases where each product earns a place in the portfolio.
Information, not advice. This article describes US Series I Savings Bond rates and rules as of May 20, 2026. It is not personal investment, tax, or financial advice. Savvy Investor Guide is not authorized or regulated by the US Securities and Exchange Commission or the Financial Conduct Authority. Rates and tax treatment are subject to change. For personal advice, consult a qualified registered investment adviser, tax professional, or financial planner in your jurisdiction. For free US consumer financial information, see consumerfinance.gov.
Key sources
- TreasuryDirect — Fiscal Service Announces New Savings Bonds Rates, May 1, 2026
- TreasuryDirect — How I-bond interest rates are determined
- TipsWatch — Treasury holds I-bond fixed at 0.90%; composite to 4.26%
- TreasuryDirect (account opening and purchase)
- Savvy Investor Guide: Premium Bonds rise to 3.8%: the UK sibling for this article
- Savvy Investor Guide: Same month, opposite direction: UK CPI 2.8% vs US CPI 3.8% (for the broader inflation context)
- Savvy Investor Guide: 401(k) Optimization Playbook 2026 (for tax-advantaged account context)
- Savvy Investor Guide: HSA Investment Strategy
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