I bonds, T-bills and the yield curve
Series I savings bonds pay 4.26% (fixed 0.90%) for bonds bought through October 31. The next rate lands November 1: the inflation half is already knowable from the CPI, the fixed half is Treasury's call. Below it, today's Treasury curve and bills (2026-10-27), and what a savings account or CD pays instead.
The November 1 reset
| CPI-U, March 2026 (NSA) | 330.213 |
| CPI-U, September 2026 (NSA) | 336.940 |
| Six-month inflation rate | 2.04% |
| Annualized inflation component | 4.08% |
| Composite if fixed stays 0.90% | 4.99% |
| Composite at 1.00% / 1.20% fixed | 5.10% / 5.30% |
Formula: fixed + 2 × semiannual inflation + fixed × semiannual inflation. The fixed rate is announced only on November 1 (page updates that day). Buying in October keeps today's 4.26% for your first six months and then switches to the new inflation rate; the fixed rate you get is the one in force when you buy.
I bond rules in one minute
- $10,000 per person per year at TreasuryDirect; trusts and businesses count separately.
- Locked for 12 months; redeem before 5 years and forfeit the last 3 months of interest.
- Federal tax deferred until you cash out; no state or local tax; tax-free for qualified education costs within income limits.
- The composite can never go below 0% even when the inflation rate is negative (as in 2009 and 2015).
- Rate changes every 6 months from your purchase month, not on November 1 itself.
Treasury yield curve 2026-10-27
| Maturity | 1 Mo | 3 Mo | 6 Mo | 1 Yr | 2 Yr | 5 Yr | 10 Yr | 30 Yr |
|---|---|---|---|---|---|---|---|---|
| Today 2026-10-27 | 4.10% | 4.22% | 4.34% | 4.50% | 4.70% | 4.82% | 4.99% | 5.30% |
| A month ago 2026-09-25 | 4.04% | 4.24% | 4.33% | 4.50% | 4.81% | 4.98% | 5.17% | 5.49% |
| Start of 2026 2026-01-02 | 3.72% | 3.65% | 3.58% | 3.47% | 3.47% | 3.74% | 4.19% | 4.86% |
2s10s spread today: +0.32 points. The curve is upward sloping: markets expect short rates to stay near here and want extra yield for the long end.
Source: US Treasury daily par yield curve. See also what the yield curve is telling you and why mortgage rates follow the 10-year.
T-bill rates coupon-equivalent, 2026-10-27
| Bill | Yield |
|---|---|
| 4-week | 4.00% |
| 8-week | 4.09% |
| 13-week | 4.15% |
| 26-week | 4.36% |
| 52-week | 4.51% |
Buy at TreasuryDirect (non-competitive, $100 minimum) or through a brokerage; interest is exempt from state and local tax.
Where cash earns the most
| Option | Rate | State tax? | Lock-up |
|---|---|---|---|
| I bond (bought by Oct 31) | 4.26% | No | 1 yr, 3-mo penalty < 5 yr |
| 13-week T-bill | 4.09% | No | 13 weeks |
| 52-week T-bill | 4.36% | No | 1 year |
| 2-year Treasury note | 4.50% | No | 2 years (sellable) |
| 12-month CD, national average | 1.76% | Yes | 1 year |
| Savings account, national average | 0.38% | Yes | None |
Bank averages from the FDIC national rates page; top online banks pay well above the average.
One year of interest
Result
Every I bond rate since 1998
| Bonds bought from | Fixed | Inflation (6-mo) | Composite |
|---|---|---|---|
| 2026-05-01 | 0.90% | 1.67% | 4.26% |
| 2025-11-01 | 0.90% | 1.56% | 4.03% |
| 2025-05-01 | 1.10% | 1.43% | 3.98% |
| 2024-11-01 | 1.20% | 0.95% | 3.11% |
| 2024-05-01 | 1.30% | 1.48% | 4.28% |
| 2023-11-01 | 1.30% | 1.97% | 5.27% |
| 2023-05-01 | 0.90% | 1.69% | 4.30% |
| 2022-11-01 | 0.40% | 3.24% | 6.89% |
| 2022-05-01 | 0.00% | 4.81% | 9.62% |
| 2021-11-01 | 0.00% | 3.56% | 7.12% |
| 2021-05-01 | 0.00% | 1.77% | 3.54% |
| 2020-11-01 | 0.00% | 0.84% | 1.68% |
| 2020-05-01 | 0.00% | 0.53% | 1.06% |
| 2019-11-01 | 0.20% | 1.01% | 2.22% |
| 2019-05-01 | 0.50% | 0.70% | 1.90% |
| 2018-11-01 | 0.50% | 1.16% | 2.83% |
| 2018-05-01 | 0.30% | 1.11% | 2.52% |
| 2017-11-01 | 0.10% | 1.24% | 2.58% |
| 2017-05-01 | 0.00% | 0.98% | 1.96% |
| 2016-11-01 | 0.00% | 1.38% | 2.76% |
| 2016-05-01 | 0.10% | 0.08% | 0.26% |
| 2015-11-01 | 0.10% | 0.77% | 1.64% |
| 2015-05-01 | 0.00% | -0.80% | -1.60% |
| 2014-11-01 | 0.00% | 0.74% | 1.48% |
| 2014-05-01 | 0.10% | 0.92% | 1.94% |
| 2013-11-01 | 0.20% | 0.59% | 1.38% |
| 2013-05-01 | 0.00% | 0.59% | 1.18% |
| 2012-11-01 | 0.00% | 0.88% | 1.76% |
| 2012-05-01 | 0.00% | 1.10% | 2.20% |
| 2011-11-01 | 0.00% | 1.53% | 3.06% |
| 2011-05-01 | 0.00% | 2.30% | 4.60% |
| 2010-11-01 | 0.00% | 0.37% | 0.74% |
| 2010-05-01 | 0.20% | 0.77% | 1.74% |
| 2009-11-01 | 0.30% | 1.53% | 3.36% |
| 2009-05-01 | 0.10% | -2.78% | -5.46% |
| 2008-11-01 | 0.70% | 2.46% | 5.64% |
| 2008-05-01 | 0.00% | 2.42% | 4.84% |
| 2007-11-01 | 1.20% | 1.53% | 4.28% |
| 2007-05-01 | 1.30% | 1.21% | 3.74% |
| 2006-11-01 | 1.40% | 1.55% | 4.52% |
| 2006-05-01 | 1.40% | 0.50% | 2.41% |
| 2005-11-01 | 1.00% | 2.85% | 6.73% |
| 2005-05-01 | 1.20% | 1.79% | 4.80% |
| 2004-11-01 | 1.00% | 1.33% | 3.67% |
| 2004-05-01 | 1.00% | 1.19% | 3.39% |
| 2003-11-01 | 1.10% | 0.54% | 2.19% |
| 2003-05-01 | 1.10% | 1.77% | 4.66% |
| 2002-11-01 | 1.60% | 1.23% | 4.08% |
| 2002-05-01 | 2.00% | 0.28% | 2.57% |
| 2001-11-01 | 2.00% | 1.19% | 4.40% |
| 2001-05-01 | 3.00% | 1.44% | 5.92% |
| 2000-11-01 | 3.40% | 1.52% | 6.49% |
| 2000-05-01 | 3.60% | 1.91% | 7.49% |
| 1999-11-01 | 3.40% | 1.76% | 6.98% |
| 1999-05-01 | 3.30% | 0.86% | 5.05% |
| 1998-11-01 | 3.30% | 0.86% | 5.05% |
| 1998-09-01 | 3.40% | 0.62% | 4.66% |
Sources: TreasuryDirect: I bond interest rates · BLS CPI-U (NSA) via the BLS API. The record composite was 9.62% (May 2022); the fixed rate peaked at 3.60% in 2000.