Overview
I-Bond Rates pulls data from the US Treasury Fiscal Data API. The composite rate consists of a fixed rate (set at purchase, never changes) plus an inflation rate (adjusts every May and November based on CPI). Historical rate data is available back to 1998.
Live Test I-Bond Rates Source →
Formula
One function covers the whole catalog: the first argument names the source, the rest are its inputs, and the "field" pair says which single value lands in the cell. Formulas covers the grammar that applies to all of them.
=VERVE("savingsbonds", "field", "compositeRate")=VERVE.CALL("savingsbonds", "field", "compositeRate")Inputs
Required inputs are positional, in the order below. Everything else is passed as a "name", value pair after them — the same shape as SUMIFS. Premium inputs are accepted on every plan but only take effect on plans that include them.
| Input | Type | Where it goes | Description |
|---|---|---|---|
periodOptionalPremium | string | "period", value | Specific issue period to lookup (YYYY-MM format, e.g., 2024-11). Omit for current rates. |
Passing an option
=VERVE("savingsbonds", "period", "2024-11")=VERVE.CALL("savingsbonds", "period", "2024-11")What lands in your sheet
The "field" pair is what makes the formula resolve to one cell. Its value is a dot-path from the table below, so swapping it is how you pull a different value — one formula per column.
Seeing everything at once
Drop the "field" pair and the formula returns the whole response instead: two columns, field name on the left and value on the right, spilling from the cell you typed in.
=VERVE("savingsbonds")=VERVE.CALL("savingsbonds")The second row's table would land on top of the first's, and every cell after the first reads #REF! (#SPILL! in Excel). Keep one per sheet, or name a field, and leave the cells below and to the right empty.
Response fields
Paths are relative to data. Each one is exactly what the "field" pair accepts, so swapping it is how you pull a different value into a cell. On a plan without a Premium field the cell reads #PREMIUM(field) rather than a value, so a locked field never looks like a real answer.
| Use as "field" | Type | Example cell value | Description |
|---|---|---|---|
period | string | 2026-10 | Issue period for the rate (YYYY-MM format) |
compositeRate | number | 4.26 | Total annual interest rate combining fixed and inflation components |
fixedRate | number | 0.9 | Fixed rate component (set at purchase, never changes) |
inflationRate | number | 1.67 | Inflation rate component (adjusts every 6 months) |
purchaseLimit | number | 10000 | Annual electronic purchase limit per person in dollars |
minimumHoldingPeriod | string | 1 year | Minimum time bond must be held before redemption |
earlyRedemptionPenalty | string | Last 3 months interest if redeemed before 5 years | Penalty for redeeming before 5 years |
taxAdvantages | string | Federal tax deferred until redemption; exempt from state/local tax; may be tax-free for education | Tax benefits of I-Bonds |
nextRateChange | string | 2026-11-01 | Date of next scheduled I-Bond rate announcement |
lastUpdated | string | 2026-09-01T15:00:29.761Z | ISO 8601 timestamp of last data refresh |
When a cell doesn't fill
A failed lookup returns readable text starting with #ERR rather than a spreadsheet error, because Excel cannot show a custom message on a real error — you would get a bare #VALUE! with no reason. The trade-off is that IFERROR() will not catch it; test with LEFT(cell, 4) = "#ERR" instead. Error handling covers the rest.
| Cell reads | What happened |
|---|---|
#ERR Not connected | No API key saved. Open the side panel and connect your account. |
#ERR Replace <name> with a cell or value | A preview formula was copied as-is. Swap the placeholder for a cell reference. |
#ERR No "x" in savingsbonds | An option name this source does not take. The message lists the ones it does. |
#ERR No data point "…" | The "field" path is not in the response. Check it against the table above. |
#PREMIUM(field) | The field exists but your plan does not include it. |
#ERR Out of credits | The cycle's credits are spent. Usage resets on your billing date. |
Before the formula works
The add-in reads the API key you saved once in the side panel — the key never goes in the formula, so a shared sheet does not leak it and a collaborator without access simply sees the last calculated values.
- Install the add-in for Google Sheets or Excel.
- Open the side panel and sign in, or paste a key from your dashboard.
- Type the formula above into any cell.
Use cases
- Investment Research
- Track I-Bond rates to optimize purchase timing around rate changes
- Financial Planning
- Factor I-Bond rates into inflation-protected savings strategies
- Rate Tracking
- Monitor I-Bond composite, fixed, and inflation rate components over time
- Historical Analysis
- Analyze historical I-Bond rates back to 1998 for trend research
Other ways to use I-Bond Rates
Set up I-Bond Rates on VerveSheets, or reach the same source a different way. Your VerveSheets account and credits work on all of them — one key, one balance.
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