October I Bonds Lock In a 0.90% Fixed Rate for 30 Years. Should You Wait Until November?

Two weeks separate two very different savings bonds. Buy a Series I bond on or before October 31 and its fixed rate is 0.90% for as long as you hold it, up to 30 years. Buy one on November 1 or later and the fixed rate is whatever the Treasury announces that morning. A closely followed forecaster expects it to be higher. The I bond rate for November 2026 is the most time-sensitive savings decision on the calendar right now, and the headline percentage hides most of the decision.

The trigger arrived on October 14. The Bureau of Labor Statistics reported that consumer prices rose 0.6% in September and 3.7% over the past year, with gasoline up 9.1% on the month. That report also closed the six-month inflation window, April through September, that sets the I bond's next variable rate. David Enna of Tipswatch calculated that inflation over those six months ran at 2.04%, which produces a new variable rate of 4.08%, up from 3.34%. He expects the Treasury to lift the fixed rate from 0.90% to at least 1.30%, with 1.40% possible, putting November purchases at a composite rate around 5.4%.

One Rate Moves, the Other Is Forever

An I bond pays two rates stacked together. The variable rate follows inflation and resets every six months for every bond in existence. The fixed rate is set on the day you buy and never changes. TreasuryDirect publishes the formula: the fixed rate, plus twice the six-month inflation rate, plus a small cross term that multiplies the two.

That structure decides everything about timing. The 4.08% variable rate is not a prize for buying in November. It reaches every outstanding I bond at its next six-month reset, including one bought last week. The fixed rate is the only part you get to choose, and you choose it exactly once. It is your guaranteed return above inflation for up to three decades.

So the useful question is not what the bond pays this month. It is which fixed rate you want attached to your money for the next 30 years. Look at that number first, every time.

Your First Twelve Months, Side by Side

Here is what $10,000 earns in its first year under each choice. The I bond rows use the published October composite of 4.26% and the Treasury's formula with the new 4.08% variable rate. One assumption is ours: for November buyers, the second six months assume inflation keeps the variable rate at 4.08% when it resets again in May 2027. The “cashed at 12 months” column reflects the rule that bonds redeemed before five years give up their last three months of interest.

The surprise is the first row. An October buyer locks in the lower fixed rate and also spends the first six months at the old 4.26% composite, because a bond keeps its purchase-month rate until its first reset. Even if the Treasury leaves the fixed rate untouched, November wins year one by about $38.

The Thirty-Year Gap Hiding in Four Tenths of a Point

A 0.40-point difference looks like rounding. Money Talks News put the value of a 1.30% fixed rate at about $1,200 over 30 years on a $10,000 bond, before compounding. Compounding is the whole story with savings bonds, since the interest is added to the bond's value every six months.

Run it as real growth, meaning dollars of today's buying power. $10,000 compounding at 0.90% above inflation for 30 years reaches about $13,084. At 1.30% above inflation it reaches about $14,733. That is a gap of roughly $1,649 in purchasing power from a single purchase date. If the Treasury goes to 1.40%, the 30-year figure climbs to about $15,175. These are our calculations from the formula, not Treasury projections. Before you place an order this month, weigh that gap against what a two-week wait actually costs you.

An I Bond Is Not a Savings Account

A rate near 5.4% will tempt people to move cash out of the bank. The fine print argues for caution. You cannot redeem an I bond at all for the first 12 months, and cashing out before five years costs the last three months of interest. Each person can also buy only $10,000 a year electronically, according to Money Talks News and Tipswatch.

So how much better is the bond than the account you already have? The High-Yield Savings Calculator answers that in a minute. Enter $10,000 at 4.27%, the top rate Bankrate lists today from Peak Bank, for 12 months. Then run it at 0.65%, Bankrate's national average, and finally at 5.41%. The middle result is what a typical bank account pays. The gap between the first and last results is the real price of giving up access for a year.

Look again at the last column. Cashed on the first possible day, every I bond row trails the top savings account: $340 to $408 against $427, and the account never locked anything up. Money you might need within a year does not belong in a bond you cannot touch for twelve months. Your emergency fund stays liquid and stays put; only money you are confident you will not need for at least a year belongs in an I bond.

What 3.7% Inflation Does to Idle Cash

The September report matters beyond bonds. At 3.7% inflation, cash sitting at the 0.65% national average loses roughly 3% of its buying power over a year. On $10,000, that is about $300 of real value gone, even though the balance looks larger. A top savings account at 4.27% stays only about half a point ahead, and that margin vanishes the day the bank cuts its rate.

You can see the slow version of that loss in the Inflation Calculator. Enter $10,000 and a 3.7% rate over five years, and check what today's balance would really buy at the end. That number is the cost of leaving money in an account that pays below inflation. Use it to decide which of your dollars need a raise.

This is where an I bond is different in kind, not just degree. Its variable rate follows prices up automatically, and the fixed rate sits on top as a guaranteed real return. A savings account promises nothing about either.

Two Weeks, One Permanent Number

Most of what an I bond pays will change many times while you own it. The fixed rate will not. If you already hold I bonds, the new 4.08% variable rate arrives at your next reset with no action needed. If you plan to buy and the money can sit for a year or more, the math points toward the November 1 announcement, when the fixed rate is set, rather than the last days of October.

Whatever you decide, decide with numbers in front of you. Run your own balance through the High-Yield Savings Calculator at today's best bank rate and at 5.41%, and know exactly what you are trading before November 1 arrives.