# US Treasury Average Interest Rates by Security Type

> US Treasury Average Interest Rates by Security Type is a paid API for AI agents from x402stock.xyz, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-16).

Returns the average interest rate the US Treasury currently pays on its outstanding debt, broken out by security type (T-Bills, Notes, Bonds, TIPS, FRNs, savings, and aggregates) for the latest reported month.

## Facts

- Endpoint: GET https://x402stock.xyz/api/v1/avg-interest-rates
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/us-treasury-average-interest-rates-by-security-type-03d700bf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_On_H2RRvucbAUVskpx1PL

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-security-type-03d700bf
```

Example prompt: What average interest rate is the US Treasury currently paying on its debt? Break it down by security type — T-Bills, Notes, Bonds, TIPS, FRNs, and the total aggregate.

## When to prefer this

Use this endpoint when you need the US government's actual average cost of borrowing broken down by debt instrument type (Bills, Notes, Bonds, TIPS, FRNs). It complements Treasury yield curve endpoints (which show market rates) by showing the weighted average rate on all outstanding debt — useful for fiscal analysis, debt cost monitoring, and macro research. Prefer this over yield-curve endpoints when the question is about what the government is actually paying, not what the market currently prices new debt at.

## Known failure modes

- Data not yet refreshed for current month — record_date may lag by several weeks
- avg_interest_rate field may be null for certain security types if Treasury has not reported
- Service unavailable or payment not processed (402 Payment Required)
- Rate limiting or upstream FiscalData API outage causing delayed or stale data

## How this service works

The average interest rate the US Treasury currently pays on its outstanding debt, broken out by security (Treasury Bills, Notes, Bonds, TIPS, FRNs, savings, and the marketable/total aggregates) for the latest reported month, in percent. No ticker needed. A read on the government's cost of borrowing that complements the /treasury-yields curve. Sourced from the US Treasury (FiscalData).

## Output

A JSON object containing the latest reported month's average interest rates paid by the US Treasury on its outstanding debt, broken out by security type (Treasury Bills, Notes, Bonds, TIPS, FRNs, savings bonds, and marketable/total aggregates), expressed as percentages, along with the record date, as_of date, source attribution, and count of series returned.

## Example request

```json
{
 "properties": ""
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "unit": "percent",
  "as_of": "2026-05-31T00:00:00.000Z",
  "count": 16,
  "rates": [
   {
    "security": "Treasury Bills",
    "security_type": "Marketable",
    "avg_interest_rate": 3.69
   },
   {
    "security": "Treasury Notes",
    "security_type": "Marketable",
    "avg_interest_rate": 3.248
   },
   {
    "security": "Treasury Bonds",
    "security_type": "Marketable",
    "avg_interest_rate": 3.413
   },
   {
    "security": "Total Marketable",
    "security_type": "Marketable",
    "avg_interest_rate": 3.386
   },
   {
    "security": "Total Interest-bearing Debt",
    "security_type": "Interest-bearing Debt",
    "avg_interest_rate": 3.353
   }
  ],
  "series": "avg_interest_rates",
  "source": "us_treasury",
  "record_date": "2026-05-31"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/us-treasury-average-interest-rates-by-security-type-03d700bf/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402stock.xyz](https://www.zero.xyz/host/x402stock.xyz/llms.txt)