About & methodology
Every number on this site traces to a U.S. Treasury source. Here is exactly how.
What this site does
Savings Bond Check answers one question well: is a given US savings bond still earning interest — and if not, since when, and what should the holder do about it? It covers Series E, EE, I, and HH bonds, current I bond rates, final-maturity rules, cashing, and inheritance paths.
What it deliberately does not do
- No redemption-value calculator. For a paper bond's dollar value, use the official TreasuryDirect Savings Bond Calculator.
- No investment, tax, or legal advice. Pages describe Treasury's official processes and link to the official source for every claim.
- No predictions — future rates appear here only after Treasury announces them.
Data sources
- I bond rates: the U.S. Treasury Fiscal Data API,
I Bonds Interest Rates dataset
(endpoint
v1/accounting/od/i_bonds_interest_rates) — the combined rate for every issue-month cohort in every semiannual rate period since September 1998 (9,690 rows this build). Cross-checked at build time against the announced rate on treasurydirect.gov; the build fails if they disagree. - Matured/outstanding totals:
Monthly Statement of the Public Debt, Table III
(endpoint
v1/debt/mspd/mspd_table_3) — matured unredeemed savings securities, monthly since 2001, and outstanding amounts by series. - Rules and procedures (maturity periods, series timelines, cashing, inheritance, tax treatment): the relevant TreasuryDirect pages, linked inline wherever a claim is made.
Methodology
The I bond composite rate is computed with Treasury's formula —
composite = fixed + 2 × inflation + fixed × inflation, floored at
zero and rounded to two decimals. Each build verifies this formula against
every row of the Fiscal Data dataset and refuses to publish if any published
rate cannot be reproduced. Per-bond "current rate" figures account for each
bond's own six-month reset schedule (a new rate window starts every sixth
month from the issue month). Maturity dates are computed from the statutory
terms: 30 years for EE and I bonds, 20 for HH, and 30 or 40 years for Series E
depending on issue date.
Update cadence
Rate data changes on Treasury's announcement dates, May 1 and November 1; MSPD figures update monthly. The site is rebuilt from the live APIs at least monthly, and every page footer shows its data-refresh date. All underlying data is US-government public domain; this site's tables are free to cite with a link.
Contact
contact@savingsbondcheck.com — corrections are welcome and applied fast.