I Bonds Still Pay 4.26% Through Oct. 31 — Buy by Oct. 29 to Lock the 0.90% Fixed Rate Before the Nov. 1 Reset

Series I savings bonds still pay a composite rate of 4.26% for bonds issued through October 31, 2026 — and that package includes a 0.90% fixed rate that stays with those bonds for life. Because October 31 falls on a Saturday, the practical move for most buyers is to submit the purchase in TreasuryDirect by Thursday, October 29, so the bond is dated in October and locks today's fixed rate before the November 1 reset. On November 1, the Treasury announces a new fixed rate and a new inflation component for bonds issued from November 2026 through April 2027. Nobody knows yet whether the next fixed rate will be higher, lower, or unchanged. This guide walks through the math, the deadline, the tax angle, and how I bonds stack up against high-yield savings accounts, CDs, and T-bills for U.S. savers who want inflation protection without leaving the Treasury's own system.

Educational disclaimer: This article is for general information only. It is not personalized investment, tax, or legal advice. Rates, purchase limits, and TreasuryDirect rules can change. Confirm current figures and cutoffs on TreasuryDirect.gov before you buy. Illustrative interest examples below use sample comparison rates and are not live offers from any bank.

Why the Oct. 29 / Nov. 1 window matters for I bonds

I bonds are unusual among popular cash products because their rate is built from two pieces: a fixed rate that is set when you buy and never changes for that bond, and an inflation rate that resets every six months based on CPI-U. The fixed rate is announced only twice a year — May 1 and November 1 — and then applies to every new I bond issued over the following six months.

For bonds issued from May 1, 2026 through October 31, 2026, the U.S. Treasury Fiscal Service set a composite rate of 4.26% with a 0.90% fixed rate. That composite applies for the first six months after your issue date. After that, your bond keeps the same 0.90% fixed rate for up to 30 years, while the inflation piece updates every six months from your issue anniversary.

If you buy with a November issue date, you get whatever fixed rate and composite the Treasury announces on November 1. Waiting can pay off if the next fixed rate rises. Waiting can also disappoint if the fixed rate falls or the inflation component softens. The October window is about locking a known 0.90% fixed rate and a known first-period composite of 4.26% — not about guessing the November announcement.

How the 4.26% composite rate is calculated

Treasury publishes the formula clearly. The annualized composite rate combines the fixed rate and the semiannual inflation rate:

Composite rate = fixed rate + (2 × semiannual inflation rate) + (fixed rate × semiannual inflation rate)

For the May–October 2026 issue window:

• Fixed rate: 0.90% (annual)
• Semiannual inflation rate: 1.67% (CPI-U rose from 324.8 in September 2025 to 330.213 in March 2026)
• Plug-in: 0.90% + 2×1.67% + (0.90% × 1.67%) = 0.90% + 3.34% + 0.01503% ≈ 4.255%, which rounds to the published 4.26%

Two details matter in practice. First, the composite is an annualized rate for that six-month earnings period; you do not receive 4.26% in six months on the full principal as a flat payout — interest accrues monthly and compounds semiannually under Treasury rules. Second, after your first six months, a new composite is calculated using the same fixed rate and the then-current inflation component. Your bond's fixed rate does not reset on November 1; only new issues get the new fixed rate.

The practical deadline: buy by Oct. 29 when Oct. 31 is a Saturday

TreasuryDirect dates electronic I bonds as of the first day of the month in which the purchase settles under its rules. Interest for a given month starts as of that issue date. Month-end weekends and federal holidays complicate the last-day scramble.

October 31, 2026 is a Saturday. In prior periods, TreasuryDirect has applied next-business-day dating when a purchase would otherwise fall on a weekend or holiday. That means a purchase submitted late in the week can be dated Monday, November 2 — which would be a November issue under the next rate schedule, not an October issue under the current 4.26% / 0.90% package.

Practical guidance used by many savers: submit the purchase by Thursday, October 29, 2026 to improve the odds of an October issue date. A Friday, October 30 submission may still work in some cases, but it is closer to the weekend dating risk. Treat this as careful timing, not a guarantee: TreasuryDirect posts exact processing and cutoff details near month-end, and those notices control. If you are buying near the deadline, log in early, confirm your bank link is verified, and leave margin for ACH timing.

Purchase timing (practical)	Likely issue month	Rate package you lock for first 6 months	Fixed rate for life of that bond
By Thu Oct. 29, 2026 (safer for Oct dating)	October 2026	4.26% composite	0.90%
Fri Oct. 30, 2026	Possibly Oct or Nov — confirm cutoffs	4.26% if Oct; new rates if Nov	0.90% if Oct; new fixed if Nov
Sat–Sun Oct. 31–Nov. 1 weekend / after Nov. 1	November 2026 (typical)	Rates announced Nov. 1, 2026	New fixed rate announced Nov. 1

If your goal is specifically the current fixed rate, do not wait until Halloween night to click Buy.

What you actually buy: electronic I bonds only, $25 to $10,000

Since January 1, 2025, new Series I bonds are electronic only through TreasuryDirect. Paper I bonds via tax refund ended on that date. Key purchase rules for most individual buyers:

• Minimum: $25
• Maximum: $10,000 electronic per Social Security number (or EIN for entities) per calendar year
• Separate limits: a child with their own SSN can have a separate $10,000 annual limit in an account you manage; entity accounts (trusts, estates, corporations, etc.) have their own EIN-based limits
• Gifts: gifted I bonds count toward the recipient's annual limit in the year the gift is delivered, not necessarily the year you bought them into a gift box
• Holding period: you must wait 12 months before redeeming; if you redeem before five years, you forfeit the last three months of interest
• Maturity: I bonds earn interest for up to 30 years

The calendar-year cap is the binding constraint for many households. If you already bought $10,000 in early 2026, you cannot add another $10,000 of electronic I bonds under the same SSN until January 2027 — even if you want to lock October's fixed rate. Couples often use both SSNs. Parents sometimes fund a child's account when that fits their estate and tax plan. Do not over-allocate cash you may need inside 12 months.

Illustrative first six months on a $10,000 I bond at 4.26%

Savers often ask what 4.26% means in dollars. Using a simple half-year annualized illustration (not a substitute for Treasury's monthly accrual and semiannual compounding schedule):

$10,000 × 4.26% × 0.5 ≈ $213 of interest over the first six-month composite period, before any later rate resets.

That is in the same neighborhood as a sample 4.00% HYSA over six months (~$200) and below a sample 5.00% twelve-month CD pro-rated for six months (~$250), if those sample rates held the whole time. The I bond's edge is not always the highest headline yield. Its edge is inflation indexing after the first period, state and local income-tax exemption, federal tax deferral until redemption or maturity, and a fixed rate that stays attached to that bond for decades.

Chart note: figures are illustrative comparisons for education only. Bank HYSA and CD rates change frequently; the CD example assumes a fixed 5.00% APY held for six months of a longer term. Your actual I bond interest follows Treasury accrual rules.

I bond vs HYSA vs CD vs T-bill: which job does each product do?

Think in roles, not in a single "winner." Competitive CDs recently advertised near 5.20% APY in some Dollar Lane market checks, and high-yield savings yields have been rising after the Federal Reserve's September 16, 2026 move to a 3.75%–4.00% target range. T-bills move with short Treasury yields and share the state-tax exemption with savings bonds. I bonds sit in a different slot: long-horizon inflation-linked savings with a purchase-year cap and a one-year lockup.

Feature	I Bond (May–Oct 2026 issue)	Sample HYSA	Sample 12-mo CD	T-bill (short)
Headline rate context	4.26% composite first 6 months; then resets with inflation + 0.90% fixed	~4.00% variable (illustrative)	~5.00%–5.20% fixed for term (illustrative)	Market yield; changes at auction
Inflation protection	Built-in via CPI-U component	None (rate can lag inflation)	None during term	Limited (short duration helps)
Liquidity	No redeem for 12 months; 3-month interest penalty if under 5 years	High (subject to bank rules)	Early-withdrawal penalty typical	Hold to maturity or sell in market
Annual purchase cap	$10,000 electronic per SSN/EIN	None (FDIC limits apply)	None (FDIC limits apply)	High TreasuryDirect/brokerage limits
State/local income tax	Exempt	Taxable	Taxable	Exempt
Federal tax timing	Can defer until redemption/maturity	Annual 1099-INT	Annual 1099-INT	Annual (OID/interest rules)
Best use case	Longer emergency sleeve / inflation hedge you can leave alone	Near-term cash & emergency fund	Known-date goals 6–24 months	Cash parking with state-tax edge

If you need the money in nine months, an I bond is the wrong tool because of the 12-month hold. If you want the highest locked yield for exactly twelve months and you can accept a bank early-withdrawal penalty, a top CD may win on dollars alone. If you live in a high-tax state and want short Treasury exposure, T-bills can beat a taxable HYSA after state tax even when the pre-tax yield looks similar. I bonds shine when you value inflation linkage plus tax features and can commit for at least a year — ideally longer so the three-month penalty window is behind you.

Taxes: federal yes, state/local no, deferral available

Interest on I bonds is subject to federal income tax. It is exempt from state and local income taxes. You may report the interest each year, or you may defer federal tax until the year you redeem the bond or it reaches final maturity — the default approach for most individual holders who buy electronically and do not elect annual reporting.

That deferral is a quiet advantage versus a HYSA or bank CD, which typically generate a Form 1099-INT every year. In a high state-tax state, the exemption alone can narrow or erase a headline yield gap. Example (illustrative only): if your marginal state income tax rate is 5%, a taxable 4.50% HYSA is roughly 4.275% after state tax, before federal tax. An I bond's state-tax-free interest does not need that haircut. Federal tax still applies eventually; plan for it when you redeem.

Education note: some holders use I bond interest for qualified higher-education expenses under the education exclusion rules if they meet income and timing tests. Those rules are specific — verify with IRS Publication 970 and a tax professional before relying on the exclusion.

Who should buy before the reset — and who should wait

Stronger fit for an October purchase:

• You still have unused 2026 electronic I bond room under your SSN (or a child's/entity account you intend to fund)
• You can leave the money untouched for at least 12 months, preferably five years to avoid the three-month interest penalty
• You want a known 0.90% fixed rate attached for up to 30 years, plus ongoing inflation adjustments
• You value state/local tax exemption and federal deferral more than squeezing the last tenth of a point from a CD
• Part of your emergency or "inflation sleeve" cash is sitting in a near-zero brick-and-mortar savings account

Weaker fit / better to wait or skip:

• You already hit the $10,000 electronic limit for 2026 under that SSN
• You might need the cash inside a year
• Your entire cash goal is a known date inside 6–18 months and a top CD clearly pays more after your tax situation
• You are trying to time a higher November fixed rate as a speculation — possible, but not a plan

Remember: buying in October locks this fixed rate on this bond. It does not prevent you from buying again in 2027 under next year's limit if the November or May rates look attractive later.

Step-by-step TreasuryDirect checklist to buy before Oct. 29

1. Create or open TreasuryDirect. Go to TreasuryDirect.gov, sign in or register with your SSN, and complete identity verification. Do this days before the deadline — not the night of October 29.
2. Link a bank account. Add your U.S. checking or savings account for ACH. Verify any micro-deposits early; unverified bank links are a common reason purchases fail at month-end.
3. Confirm your 2026 limit room. Check prior 2026 I bond purchases under that SSN. Stay at or under $10,000 electronic for the calendar year.
4. Decide registration. Individual, primary owner with secondary, entity, or minor account — match the registration to how you want ownership and estate handling to work.
5. Buy Series I (electronic). Choose the amount ($25 minimum, up to remaining annual room). Review the issue-date language on the confirmation screen.
6. Submit by Oct. 29 if you want October dating. Keep a screenshot or PDF of the purchase confirmation. Interest will accrue from the issue date under Treasury rules.
7. Set a calendar reminder for 12 months. Note earliest penalty-free window after five years if you care about the three-month interest rule.
8. Do not chase paper. New paper I bonds via tax refund ended January 1, 2025. Plan on electronic only.
9. Revisit after Nov. 1. Read the new fixed and inflation rates. Decide whether a 2027 purchase (or a different product) fits the rest of your cash plan.

What happens to bonds you already own when rates reset?

Nothing spooky. Existing I bonds do not jump to the new fixed rate announced on November 1. Each bond keeps the fixed rate assigned when it was issued. What does change every six months — on that bond's own schedule — is the inflation component used to build its next composite rate. A bond bought in October 2026 will use the May–October 2026 fixed rate of 0.90% for life, and its first composite of 4.26% for the first six months, then a new composite at the six-month mark using the inflation rate then in effect.

If you bought earlier in 2026 under the same 0.90% fixed rate window, you already have that fixed rate. The October deadline is mainly for people who still have purchase room and want an October issue before the next announcement cycle.

FAQ: Can the composite go to zero? Can I lose principal?

Can the composite rate go to zero? The formula can produce a very low composite if inflation is negative enough to offset the fixed rate, but Treasury's rules include a floor so the composite rate is not below zero. You do not get a negative interest rate that reduces principal for deflation in the way some inflation-linked market securities can. Always read the current TreasuryDirect I bond rate explanation for the floor language.

Can I lose principal? If you hold an electronic I bond and redeem after the minimum holding period, you receive principal plus accrued interest minus any early-redemption interest penalty if applicable. I bonds are backed by the U.S. government. Market price risk like a long Treasury bond fund is not the same issue here because you redeem with Treasury rather than selling on a secondary market at a discount.

FAQ: Should I drain my HYSA to max I bonds?

Usually no. Keep a true emergency fund in a liquid HYSA or similar account you can reach without a 12-month wait. Use I bonds for the slice of cash you are willing to park for a year or more as an inflation-aware savings sleeve. A common pattern is: three to six months of expenses in HYSA, then I bonds up to the annual limit for longer-hold cash, then CDs or T-bills for dated goals. Your mix depends on income stability, job risk, and upcoming expenses — not on a single blog checklist.

FAQ: What if November's fixed rate is higher?

Then buyers who waited may get a better lifetime fixed rate on new issues. That is the trade-off. Historically, the fixed rate has moved both up and down across May/November announcements. The 0.90% fixed rate for the current window is already known; November's number is not. If locking a known fixed rate and known first composite matters more to you than gambling on the next print, October still makes sense — especially if you were going to buy I bonds this year anyway and still have limit room.

Putting the numbers next to today's cash market

Context from the broader U.S. cash market in mid-October 2026 helps set expectations without turning this into a rate-shopping roundup. After the Fed's September 16 hike to a 3.75%–4.00% federal funds target range, competitive high-yield savings yields moved up, and some CDs advertised near the low-to-mid 5% range. Those products are excellent for liquid cash and dated goals. They do not automatically replace I bonds, because they lack the CPI-linked reset and the same tax package.

A simple decision filter:

• Need money in under 12 months? HYSA, short T-bills, or a short CD — not a new I bond.
• Want a locked bank yield for 12 months and can accept penalties? Shop CDs; compare after-tax if your state taxes interest heavily.
• Want inflation linkage + state-tax exemption + deferral, and can wait a year? Use remaining 2026 I bond room before the October dating cutoff if you like the 0.90% fixed rate.
• Unsure about November? Buy only the amount you were already comfortable allocating; leave other cash in HYSA until the Nov. 1 announcement.

Illustrative $10,000 for ~6 months	Approx. interest	What you give up / gain
I bond at 4.26% annualized (first period)	~$213	12-month lockup; inflation resets later; state tax exempt; federal deferrable
Sample HYSA at 4.00%	~$200	Full liquidity; rate can fall; taxable annually; no fixed lifetime component
Sample 12-mo CD at 5.00% (6-mo slice)	~$250	Higher dollars if held; early-withdrawal penalty risk; taxable; no CPI link

Again: these are teaching numbers, not a recommendation to buy any specific bank product today.

Bottom line

I bonds issued through October 31, 2026 still carry a 4.26% composite for the first six months and a 0.90% fixed rate for the life of the bond. Because October 31 is a Saturday, aim to purchase in TreasuryDirect by Thursday, October 29, 2026 if you want an October issue date — and verify TreasuryDirect's own cutoff notices as the date approaches. November 1 brings a new fixed rate and inflation component for the next six-month issue window. I bonds will not always beat the hottest CD on raw yield, but they remain one of the cleanest ways for U.S. households to add inflation-linked, state-tax-advantaged savings inside a hard $10,000 annual electronic cap. Use them for money you can leave alone; keep true emergency cash liquid; and treat the October deadline as a scheduling problem, not a hype cycle.

Sources

U.S. Department of the Treasury / TreasuryDirect — I bonds interest rates (composite 4.26%, fixed 0.90% for issues May 1, 2026–October 31, 2026): treasurydirect.gov/savings-bonds/i-bonds/i-bonds-interest-rates/. Fiscal Service news release, May 1, 2026 (Series I 4.26%, fixed 0.90%, CPI-U September 2025 to March 2026 increase of 1.67%): treasurydirect.gov/news/2026/release-05-01-rates/. Purchase, redemption, tax, and electronic-only rules: TreasuryDirect I bond pages. Comparison HYSA/CD figures in this article are illustrative samples for education, not live offers.