# POST /api/v1/billing/grandfather

> Grandfather the current business (superuser only)

- **Tag:** billing
- **Operation ID:** `grandfather_business`

## Description

Mark the current business as grandfathered so it keeps access without billing.

**Effect:**
- Sets ``plan_tier`` to ``grandfathered`` and ``billing_status`` to ``active``
- Clears ``trial_ends_at``
- Grants the default grandfathered add-on set

**Prerequisites:**
- Caller must be a superuser. Regular users never see this in the UI
  and receive 403 if they call the endpoint directly.

## Authentication

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

## Responses

### 201 — Successful Response

Schema: `SuccessEnvelope_GrandfatherBusinessResponse_`

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

### 401 — Unauthorized - Missing/invalid token 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.

### 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/billing/grandfather' \
  -H 'Authorization: Bearer dz_your_token' \
  -H 'x-business-id: YOUR_BUSINESS_ID'
```

### JavaScript

```javascript
const response = await fetch('https://api.ondayzero.com/api/v1/billing/grandfather', {
  method: 'POST',
  headers: {
    Authorization: 'Bearer dz_your_token',
    'x-business-id': 'YOUR_BUSINESS_ID',
  },
});
const data = await response.json();
```

### Python

```python
import httpx

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

response = httpx.post("https://api.ondayzero.com/api/v1/billing/grandfather", headers=headers)
data = response.json()
```

## See also

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