# Coverage change feed

URL: https://docs.healthcare.dev/reference/coverage/coverage-change-feed

```http
GET https://api.healthcare.dev/v1/coverage/changes
```

Pro plan and up (403 `plan-upgrade-required` below Pro). Material changes to coverage documents as we detect them: a code or diagnosis list, coverage status, an effective or retirement date, or the criteria changed; a document was added or retired. Each event names what changed (`fields_changed`), the procedure codes whose answers may differ (`affected_codes`), the effective date and the source page to check (`evidence`). Formatting-only revisions are never listed. Oldest first by default; `order=desc` for the most recent first. Page with `cursor`. The dataset change feed (`/v1/changes`) lists dataset releases; this one lists source documents.

Requires an API key: `Authorization: Bearer hdev_live_...`. See [Authentication](/authentication).

## Query parameters

| Name | Type | Required | Description | Example |
| --- | --- | --- | --- | --- |
| `source_type` | "coverage" | no | Kind of source: `coverage` (more kinds later) | `coverage` |
| `payer` | string | no | Payer whose documents changed: `medicare` (more payers later) | `medicare` |
| `code` | string | no | Only changes affecting this procedure code | `11720` |
| `since` | string (date-time) | no | Only changes detected after this time |  |
| `limit` | integer | no | Page size, 1 to 1000 (default 100) | `100` |
| `order` | "asc" \| "desc" | no | asc = oldest first (default), desc = newest first | `asc` |
| `cursor` | string | no | Opaque cursor from `links.next` |  |
| `view` | "compact" \| "standard" \| "full" | no | How much of each record to return (default `full`). `compact`: `id`, `document`, `change`, `fields_changed`, `affected_codes`, `effective_date` (fewest tokens, for agents). `standard`: every field except `type`, `source_type`. `full`: every field. | `compact` |
| `fields` | string | no | Comma-separated fields to return instead of a view. Valid fields: `id`, `type`, `source_type`, `payer`, `document`, `change`, `kind`, `fields_changed`, `affected_codes`, `affected_dx_count`, `effective_date`, `detected_at`, `evidence`. | `id,document,change` |

## Examples

**curl**

```sh
curl "https://api.healthcare.dev/v1/coverage/changes?limit=100" \
  -H "Authorization: Bearer $HDEV_API_KEY"
```

**TypeScript**

```ts
const res = await fetch("https://api.healthcare.dev/v1/coverage/changes?limit=100", {
  headers: { Authorization: `Bearer ${process.env.HDEV_API_KEY}` },
});
const { data, meta } = await res.json();
```

**Python**

```python
import os
import requests

res = requests.get("https://api.healthcare.dev/v1/coverage/changes?limit=100", headers={"Authorization": f"Bearer {os.environ['HDEV_API_KEY']}"})
body = res.json()
```

## Response

Material coverage changes

```json
{
  "data": [
    {
      "id": "string",
      "type": "coverage.changed",
      "source_type": "coverage",
      "payer": "string",
      "document": {
        "id": "string",
        "type": "lcd",
        "title": "string",
        "version_before": 1,
        "version_after": 1
      },
      "change": "added",
      "kind": "material",
      "fields_changed": [
        "document"
      ],
      "affected_codes": [
        "string"
      ],
      "affected_dx_count": 1,
      "effective_date": "2026-10-01",
      "detected_at": "2026-10-24T12:00:00Z",
      "evidence": {
        "url": "string",
        "anchor": "string"
      }
    }
  ],
  "meta": {
    "source": "cms-icd10",
    "data_version": "2026.1",
    "retrieved_at": "2026-10-24T12:00:00Z",
    "license": "Public domain (CMS). Reference data, not medical advice."
  },
  "links": {
    "self": "/v1/coverage/changes?limit=100",
    "next": "/v1/coverage/changes?limit=100&cursor=eyJrIjoiRTExLjkifQ"
  }
}
```

### Fields

| Field | Type | Always present | Description |
| --- | --- | --- | --- |
| `id` | string | yes | Stable event id; order by it |
| `type` | "coverage.changed" | yes |  |
| `source_type` | "coverage" | yes |  |
| `payer` | string | yes | `medicare` (CMS) for now |
| `document` | object | yes |  |
| `change` | "added" \| "revised" \| "removed" | yes | `added`: new or newly in effect; `removed`: retired or withdrawn |
| `kind` | "material" | yes |  |
| `fields_changed` | "document" \| "status" \| "codes" \| "dx_supporting" \| "dx_not_supporting" \| "dx_groups" \| "states" \| "coverage_level" \| "effective_date" \| "original_effective_date" \| "retire_date" \| "criteria" \| "coding_rules" \| "billing_codes" \| "benefit_categories" \| "related_documents" \| "contractors" \| "title" \| "revision_history" \| "background_text" \| "formatting" \| "row_order" \| "version"[] | yes |  |
| `affected_codes` | string[] | yes | Procedure codes whose answers may have changed (identifiers only) |
| `affected_dx_count` | integer | yes | ICD-10-CM codes added to or removed from lists |
| `effective_date` | string \| null (date) | yes |  |
| `detected_at` | string (date-time) | yes | When we saw the change in the source |
| `evidence` | DerivedEvidence | yes |  |

## Errors

Errors are `application/problem+json` ([RFC 9457](https://www.rfc-editor.org/rfc/rfc9457)). Branch on `type`, not on `title`. See [Errors](/errors).

| Status | `type` | When |
| --- | --- | --- |
| 400 | `invalid-request` | A parameter or the body failed validation; `errors` lists each field. |
| 401 | `unauthorized` | Missing, malformed or revoked API key. |
| 403 | `plan-upgrade-required` | The plan doesn't include this feature; `required_plan` names the plan that does. |
| 404 | `not-found` | No record with that id (retired records are still returned). |
| 429 | `rate-limited / quota-exceeded` | Too many requests per second (retry after `Retry-After`), or the monthly quota is used up. |
| 503 | `dataset-unavailable / unavailable` | The dataset has no published version yet, or the service is degraded. |