> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rcintell.com/llms.txt
> Use this file to discover all available pages before exploring further.

# What is a CCN?

> Medicare Certification Number explained

A **CMS Certification Number (CCN)** is a 6-character identifier assigned to every Medicare-certified healthcare facility. The CCN encodes the facility's state, type, and sequence number.

## CCN format

```
[SS][TTTT]
 │    │
 │    └── Facility type + sequence (4 digits)
 └─────── State code (2 digits)
```

| Digits | Name                     | Description                                                        |
| ------ | ------------------------ | ------------------------------------------------------------------ |
| 1-2    | State code               | Maps to a US state or territory (01=AL, 02=AK, ... 53=territories) |
| 3-6    | Facility type + sequence | Encodes the type of facility and a unique sequence number          |

## Facility type ranges

| Range     | Facility Type                      |
| --------- | ---------------------------------- |
| 0001-0879 | Short-term (acute care) hospitals  |
| 1300-1399 | Critical Access Hospitals (CAH)    |
| 3000-3299 | Home Health Agencies               |
| 3300-3399 | Home Health Agency sub-units       |
| 4000-4499 | Skilled Nursing Facilities (SNF)   |
| 5000-6499 | Rehabilitation hospitals and units |

## Example

**CCN: 170001**

* State code `17` → Kansas
* Facility range `0001` → Short-term hospital, first in sequence
* This is the first short-term acute care hospital registered in Kansas

## Why CCN matters

The CCN is the root of RCI's knowledge graph. From a single CCN, the platform resolves:

* **L1**: State → GPCI values, MAC jurisdiction, Medicaid program
* **L2**: Facility type → Payment system, billing form, TOB codes
* **L3-L6**: Additional layers build on the CCN-derived context

## RCI and CCNs

Every facility in RCI is identified by its CCN. Register a facility to cache its knowledge layers:

```bash theme={null}
curl -X POST https://api-dev.rcintell.com/v1/facilities/ \
  -H "X-API-Key: kp_test_..." \
  -H "Content-Type: application/json" \
  -d '{"ccn": "170001", "name": "Sunflower Medical Center", "state": "KS"}'
```

Or resolve knowledge without registering:

```bash theme={null}
curl -X POST https://api-dev.rcintell.com/v1/knowledge/resolve \
  -H "X-API-Key: kp_test_..." \
  -H "Content-Type: application/json" \
  -d '{"ccn": "170001", "cpt": "99213"}'
```