---
url: https://thresholds.pages.dev/i-bonds/rate-history/
title: "I Bond Rate History: Every Rate Since 1998"
updated: 2026-09-07
site: Thresholds
sources:
  - https://api.fiscaldata.treasury.gov/services/api/fiscal_service/v1/accounting/od/i_bonds_interest_rates
  - https://www.treasurydirect.gov/savings-bonds/i-bonds/i-bonds-interest-rates/
---

# I Bond Rate History: Every Rate Since 1998

Every Series I savings bond fixed rate, semiannual inflation rate and composite rate since September 1998 — chart, table and CSV.

Every fixed, semiannual inflation and composite rate since September 1998, by six-month announcement window, from September 1998 to the current period. Available as a table and as a CSV at /i-bonds/rate-history.csv with the columns period, start, end, fixed_rate, semiannual_inflation_rate, composite_rate.

Treasury sets I bond rates twice a year, on May 1 and November 1, so the series is a step function: between two announcements no rate moves. Each window carries a fixed rate, which a bond bought in that window keeps for 30 years, and a semiannual inflation rate, which applies to every I bond whose own six-month period begins in that window. The composite is fixed rate + 2 × semiannual inflation + (fixed × semiannual inflation ÷ 100), floored at 0%.

Two features matter for reading it. The highest composite an I bond has ever started at was 9.62%, for bonds issued May 2022. And in the windows beginning May 2009 and May 2015 the semiannual inflation rate was negative, so the formula produced a negative number and the composite floored at 0%: an I bond earns nothing for those six months rather than losing value.

The current period is 0.90% fixed plus 1.67% semiannual inflation, giving 4.26%. The next announcement is November 1, 2026.

## Sources

- [Treasury Fiscal Data — I Bonds Interest Rates](https://api.fiscaldata.treasury.gov/services/api/fiscal_service/v1/accounting/od/i_bonds_interest_rates)
- [TreasuryDirect — I bonds interest rates](https://www.treasurydirect.gov/savings-bonds/i-bonds/i-bonds-interest-rates/)

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Information, not advice. Figures verified 2026-09-07. https://thresholds.pages.dev/i-bonds/rate-history/