I bond rates · May 2015 – October 2015
I Bond Rate for May 2015 – October 2015
Announced May 2015 1 by the Treasury: a fixed rate of 0.00%, a semiannual inflation rate of -0.80%, and the 0.00% composite those two produce.
A bond bought in this period earned 0.00% for its first six months and keeps its 0.00% fixed rate for life. With the current inflation rate of 1.67% it earns 3.34% in May 2026 – October 2026.
The May 2015 – October 2015 composite, worked
Treasury's formula: fixed rate + (2 × semiannual inflation rate) + (fixed rate × semiannual inflation rate), rounded to four decimals, and never below zero.
What this cohort has earned since
Its fixed rate never changes; each later period applies that period's inflation rate to it. Rates take effect on the bond's own six-month anniversaries, not on the announcement date.
| Period | Inflation rate | This cohort's fixed | Composite |
|---|---|---|---|
| May 2026 – October 2026 | 1.67% | 0.00% | 3.34% |
| November 2025 – April 2026 | 1.56% | 0.00% | 3.12% |
| May 2025 – October 2025 | 1.43% | 0.00% | 2.86% |
| November 2024 – April 2025 | 0.95% | 0.00% | 1.90% |
| May 2024 – October 2024 | 1.48% | 0.00% | 2.96% |
| November 2023 – April 2024 | 1.97% | 0.00% | 3.94% |
| May 2023 – October 2023 | 1.69% | 0.00% | 3.38% |
| November 2022 – April 2023 | 3.24% | 0.00% | 6.48% |
| May 2022 – October 2022 | 4.81% | 0.00% | 9.62% |
| November 2021 – April 2022 | 3.56% | 0.00% | 7.12% |
| May 2021 – October 2021 | 1.77% | 0.00% | 3.54% |
| November 2020 – April 2021 | 0.84% | 0.00% | 1.68% |
| May 2020 – October 2020 | 0.53% | 0.00% | 1.06% |
| November 2019 – April 2020 | 1.01% | 0.00% | 2.02% |
| May 2019 – October 2019 | 0.70% | 0.00% | 1.40% |
| November 2018 – April 2019 | 1.16% | 0.00% | 2.32% |
| May 2018 – October 2018 | 1.11% | 0.00% | 2.22% |
| November 2017 – April 2018 | 1.24% | 0.00% | 2.48% |
| May 2017 – October 2017 | 0.98% | 0.00% | 1.96% |
| November 2016 – April 2017 | 1.38% | 0.00% | 2.76% |
| May 2016 – October 2016 | 0.08% | 0.00% | 0.16% |
| November 2015 – April 2016 | 0.77% | 0.00% | 1.54% |
| May 2015 – October 2015 | -0.80% | 0.00% | 0.00% (floored) |
Source: TreasuryDirect — I bonds interest rates (fixed-rate and inflation-rate history). Composites are recomputed with Treasury's formula and checked against Treasury's published figures before publication. Bonds cashed before five years forfeit the last three months of interest.
Informational only, not financial or tax advice.
Last reviewed: May 2026 announcement · snapshot built 2026-10-26 from treasurydirect.gov.
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