Buy I bonds before November 1, or wait?
What a bond bought before the rate change keeps, what one bought after gets, and Treasury's purchase cut-off.
Treasury announces the November 2026 I bond rate on November 1, 2026. Half of it is already known: the 2.04% inflation rate set by published CPI. The other half, the fixed rate, is the only thing that changes the answer, because a bond keeps its fixed rate for 30 years.
- A bond issued October 2026 keeps the 0.90% fixed rate for life and earns 4.26% for its first six months, then 5.00% from April 2027 (the 2.04% inflation rate already set for November 2026 plus its 0.90% fixed rate).
- A bond issued November 2026 gets whatever fixed rate Treasury announces on November 1, 2026, plus the same 2.04% inflation rate for its first six months. Only the fixed rate is unknown.
- The fixed rate never changes, so it is the only lasting difference: every 0.10 points of fixed rate is about 0.10 points a year for as long as you hold the bond (TreasuryDirect).
- I bonds earn interest from the first day of the month you buy them (TreasuryDirect), so a bond bought late in October earns October's interest in full.
- The issue date is the month Treasury receives your funds (before midnight Eastern), and a request at the end of the month can be issued the following month (TreasuryDirect FAQ). The last business day of October is Friday, October 30, 2026. October 31 is a Saturday; Treasury moves a purchase dated on a non-business day to the next business day, which falls in the next month.
Buying in October vs buying in November
Every I bond earns its own fixed rate plus the inflation rate in force, and moves to a new inflation rate every six months counted from its issue month (TreasuryDirect: I bond interest rates).
| Issued October 2026 | Issued November 2026 | |
|---|---|---|
| Fixed rate, for life | 0.90% | announced November 1, 2026 |
| First six months | 4.26% | new fixed + 2.04% inflation (table below) |
| From April 2027 | 5.00% | still in its first six months |
| Interest from | October 1, 2026 | November 1, 2026 |
| Can be cashed from | October 2027 | November 2027 |
What a November 2026 bond would earn for its first six months, by the fixed rate Treasury might announce (Treasury's composite formula with the 2.04% inflation rate):
| If the new fixed rate is | First six months | Lasting difference |
|---|---|---|
| 0.50% | 4.59% | -0.40 pts a year vs 0.90%, for life |
| 0.60% | 4.69% | -0.30 pts a year vs 0.90%, for life |
| 0.70% | 4.79% | -0.20 pts a year vs 0.90%, for life |
| 0.80% | 4.90% | -0.10 pts a year vs 0.90%, for life |
| 0.90% (unchanged) | 5.00% | same as an October bond |
| 1.00% | 5.10% | +0.10 pts a year vs 0.90%, for life |
| 1.10% | 5.20% | +0.20 pts a year vs 0.90%, for life |
| 1.20% | 5.30% | +0.30 pts a year vs 0.90%, for life |
| 1.30% | 5.41% | +0.40 pts a year vs 0.90%, for life |
| 1.40% | 5.51% | +0.50 pts a year vs 0.90%, for life |
| 1.50% | 5.61% | +0.60 pts a year vs 0.90%, for life |
| 1.60% | 5.71% | +0.70 pts a year vs 0.90%, for life |
Treasury does not publish how it sets the fixed rate. One reference point people use is the 5-year TIPS real yield: it was 2.36% on October 28, 2026 and averaged 2.09% over the six months before November 2026 (Treasury par real yield curve). At past announcements with a similar six-month average, Treasury set fixed rates of May 2006 (1.40%), November 2006 (1.40%), May 2007 (1.30%), November 2007 (1.20%), November 2023 (1.30%), May 2024 (1.30%), November 2024 (1.20%). That is history, not a forecast: the full fixed rate and real yield table shows how loosely the two move.
The purchase cut-off
TreasuryDirect: "The issue date of your bond is the first day of the month in which the Treasury receives funds for the purchase of the security", funds must be received before midnight Eastern Time to count for a day, and "if you make a purchase request at the end of the month, your bond's issue date may be the following month depending upon when funds are received". A purchase date on a non-business day is moved to the next business day (TreasuryDirect FAQ).
So the realistic last day to get an October issue date is the last business day, Friday, October 30, 2026, and Treasury does not promise even that. New accounts take longer than a purchase in an existing account.
How much you can buy
Each Social Security Number can buy up to $10,000 in electronic I bonds per calendar year, from $25 to the penny, and gift bonds count toward the recipient's limit, not the giver's (TreasuryDirect: purchase limits). Paper I bonds are no longer sold (TreasuryDirect: I bonds). Both October and November purchases count toward 2026's limit.
Before buying either: an I bond can't be cashed for 12 months, and cashing before 5 years costs the last 3 months of interest (TreasuryDirect). See cashing early.
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Frequently asked questions
Should I buy I bonds before November 1 or wait?
It depends only on the fixed rate Treasury announces, which nobody knows in advance. Buying in October locks 0.90% fixed for life; buying in November locks the new fixed rate. If the new fixed rate is above 0.90%, the later bond earns more every year; if it is lower, the earlier bond does. Both get the same 2.04% inflation rate.
What is the last day to buy an I bond in October 2026?
Treasury dates the bond by the month it receives your funds, before midnight Eastern, and says end-of-month requests can be issued the next month. The last business day of October 2026 is Friday, October 30, 2026.
Do I get a full month of interest if I buy at the end of the month?
Yes. TreasuryDirect says I bonds earn interest from the first day of the month you buy them.
When does an I bond's rate change?
Every six months from its issue month. A bond issued in October changes on April 1 and October 1; one issued in November on May 1 and November 1.
How much can I put in I bonds a year?
$10,000 in electronic I bonds per Social Security Number per calendar year, plus gift bonds, which count toward the recipient's limit.
More: what every existing I bond will earn · fixed rate history · every I bond rate since 1998.
Rules are quoted from TreasuryDirect pages linked where used (read 2026-10-29). Rates come from Treasury Fiscal Data and TreasuryDirect, and composites use Treasury's published formula. This site is independent of the Treasury and is not investment advice.