# US Treasury Average Interest Rates by Instrument

> US Treasury Average Interest Rates by Instrument is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-29).

Returns the average interest rate the US Treasury currently pays on its debt, broken down by instrument type (bills, notes, bonds, TIPS, FRNs, total), plus the rate from one year prior.

## Facts

- Endpoint: POST https://api.vextorium.com/tipos-medios-deuda-eeuu-pago?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/us-treasury-average-interest-rates-by-instrument-d31b65f3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_iFjjYyCpmnPyvaSE2yH5S

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability us-treasury-average-interest-rates-by-instrument-d31b65f3 -d '<json body>'
```

Example prompt: What average interest rates is the US Treasury currently paying on its debt — can you break it down by instrument like bills, notes, bonds, and TIPS, and show me how each compares to a year ago?

## When to prefer this

Use this endpoint when you need authoritative, official US Treasury data on average debt costs by instrument type — particularly for macroeconomic analysis, fiscal research, fixed income context, or year-over-year borrowing cost comparisons. Prefer this over market yield APIs (which show current market prices) when you specifically want the weighted average rate Treasury is actually paying on outstanding securities, not the current auction or secondary market yield.

## Known failure modes

- Data not yet updated for the current period — response may reflect the most recent available month
- Empty or null values for some instruments if Treasury has not issued that instrument type recently
- Network or upstream API timeout resulting in no response
- Malformed POST body (wrong bodyType or missing required input wrapper) causing a 400 error

## How this service works

Average interest rate the US Treasury pays on its debt by instrument (bills, notes, bonds, TIPS, FRNs...) and total, with the rate one year earlier. US Treasury, public domain.

## Output

Returns a JSON object with the reference date, data source attribution, and an array of instruments (e.g. Treasury Bills, Treasury Notes, Treasury Bonds, TIPS, FRNs, Total Marketable, Total Non-Marketable, Total Interest-Bearing Debt). Each instrument entry includes its type category (Marketable/Non-Marketable), instrument name, current average interest rate as a percentage, and the equivalent rate from one year earlier.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "required": [],
     "properties": {}
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": [
      "object",
      "null"
     ],
     "properties": {
      "fecha": {
       "type": [
        "string",
        "null"
       ]
      },
      "fuente": {
       "type": [
        "string",
        "null"
       ]
      },
      "instrumentos": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": [
         "null",
         "object"
        ],
        "properties": {
         "tipo": {
          "type": [
           "null",
           "string"
          ]
         },
         "instrumento": {
          "type": [
           "null",
           "string"
          ]
         },
         "tipo_medio_pct": {
          "type": [
           "null",
           "number"
          ]
         },
         "hace_un_anio_pct": {
          "type": [
           "null",
           "number"
          ]
         }
        }
       }
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "fecha": "2026-08-31",
  "fuente": "U.S. Treasury, Average Interest Rates on U.S. Treasury Securities (dominio público)",
  "instrumentos": [
   {
    "tipo": "Marketable",
    "instrumento": "Treasury Bills",
    "tipo_medio_pct": 3.788,
    "hace_un_anio_pct": 4.283
   },
   {
    "tipo": "Marketable",
    "instrumento": "Treasury Notes",
    "tipo_medio_pct": 3.345,
    "hace_un_anio_pct": 3.087
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/us-treasury-average-interest-rates-by-instrument-d31b65f3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.vextorium.com](https://www.zero.xyz/host/api.vextorium.com/llms.txt)