# POST /api/v1/credit/scorecard-versions/{version_id}/backtest

> Backtest a version over a cohort

- **Tag:** credit
- **Operation ID:** `backtest_scorecard_version`

## Description

Console operators only. Queues a run of the version over up to 500 businesses and returns the job; poll `GET /credit/scorecard-backtests/{id}` until `status` is `completed` or `failed`. Each business is measured once and scored; pass `compare_version_id` to score it under a second version too and learn which businesses come out differently. Measures only: no assessment is created and no event is emitted.

## Authentication

Bearer token in `Authorization` header.
Required header: `x-business-id: <business uuid>`.

## Parameters

- `version_id` (path, string, required)

## Request body

Schema: `ScorecardBacktestRequest`

- `business_ids` (array · string) — The cohort, explicitly. Each must be accessible to the caller.
- `firm_id` (string) — Or: every business the caller can access in this firm (workspace). Ignored when `business_ids` is given.
- `limit_mode` (string) (one of: fixed, line_limit, per_business, none) — Where each business's requested limit comes from. fixed: `requested_limit_cents` for all. line_limit: the business's existing credit line on this operator. per_business: `requested_limits_cents`. none: no limit is supplied.
- `requested_limit_cents` (integer)
- `requested_limits_cents` (object) — Business id to requested limit, in cents.
- `requested_term_days` (integer)
- `as_of` (string · date)
- `compare_version_id` (string) — Also run this version and report which businesses come out differently.

## Responses

### 202 — Successful Response

Schema: `SuccessEnvelope_ScorecardBacktestResponse_`

- `success` (boolean)
- `message` (string)
- `code` (string)
- `data` (ScorecardBacktestResponse)

### 400 — Bad Request - Invalid input

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

### 401 — Unauthorized - Missing or expired token, an MCP OAuth token used against the REST API, or no access to this business

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

### 403 — Forbidden - Insufficient permissions

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

### 404 — Not Found - Resource does not exist

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

### 422 — Validation Error

Schema: `ErrorResponse`

- `error` (string · required) — Error category: `validation_error`, `unauthorized`, `forbidden`, `not_found`, `conflict`, `rate_limited`, `server_error`, or `service_unavailable`.
- `message` (string · required) — Human-readable explanation, safe to show to end users.
- `code` (string · required) — Stable machine-readable code in `CATEGORY_NNN` form (e.g. `NOT_FOUND_006`, `AUTH_010`, `GEN_002`).
- `request_id` (string) — Correlation id for support requests. Echoes the `x-request-id` request header when one was supplied.
- `errors` (object) — Field-level validation messages keyed by field name. Present on 400/422 validation failures only.

## Code samples

### cURL

```bash
curl -X POST 'https://api.ondayzero.com/api/v1/credit/scorecard-versions/{version_id}/backtest' \
  -H 'Authorization: Bearer dz_your_token' \
  -H 'x-business-id: YOUR_BUSINESS_ID' \
  -H 'Content-Type: application/json' \
  -d '{
  "business_ids": [],
  "firm_id": "string",
  "limit_mode": "fixed",
  "requested_limit_cents": 0,
  "requested_limits_cents": {},
  "requested_term_days": 0
}'
```

### JavaScript

```javascript
const response = await fetch('https://api.ondayzero.com/api/v1/credit/scorecard-versions/{version_id}/backtest', {
  method: 'POST',
  headers: {
    Authorization: 'Bearer dz_your_token',
    'x-business-id': 'YOUR_BUSINESS_ID',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
  "business_ids": [],
  "firm_id": "string",
  "limit_mode": "fixed",
  "requested_limit_cents": 0,
  "requested_limits_cents": {},
  "requested_term_days": 0
}),
});
const data = await response.json();
```

### Python

```python
import httpx

headers = {
    "Authorization": "Bearer dz_your_token",
    "x-business-id": "YOUR_BUSINESS_ID",
}

payload = {'business_ids': [],
 'firm_id': 'string',
 'limit_mode': 'fixed',
 'requested_limit_cents': 0,
 'requested_limits_cents': {},
 'requested_term_days': 0}

response = httpx.post("https://api.ondayzero.com/api/v1/credit/scorecard-versions/{version_id}/backtest", headers=headers, json=payload)
data = response.json()
```

## See also

- HTML version: https://www.ondayzero.com/docs/reference/credit/backtest-scorecard-version
- OpenAPI slice: https://www.ondayzero.com/docs/reference/credit/backtest-scorecard-version/openapi.json
- Other endpoints in **credit**: https://www.ondayzero.com/docs/reference/credit (markdown bundle: https://www.ondayzero.com/docs/reference/credit.md, OpenAPI: https://www.ondayzero.com/docs/reference/credit/openapi.json)
- Endpoint catalog: https://www.ondayzero.com/docs/reference/index.md