# Medicare Beneficiary Identifier (MBI) lookup
Source: https://www.stedi.com/docs/healthcare/mbi-lookup

***

title: Medicare Beneficiary Identifier (MBI) lookup
sidebarTitle: MBI lookup for CMS checks
---------------------------------------

A [Medicare Beneficiary Identifier (MBI)](https://www.cms.gov/training-education/partner-outreach-resources/new-medicare-card/medical-beneficiary-identifiers-mbis) is a unique, randomly-generated identifier assigned to individuals enrolled in Medicare. You must include the patient's MBI in every eligibility check you submit to the Centers for Medicare and Medicaid Services ([payer ID: CMS](https://www.stedi.com/healthcare/network/cms)).

When patients don't know their MBI, you can use Stedi's eligibility APIs to perform an MBI lookup instead of a standard eligibility check. Stedi returns a complete eligibility response containing the patient’s coverage status and their MBI for future reference.

<Warning>
  There is an additional cost to perform MBI lookups with Stedi's eligibility
  check APIs. Visit [pricing](https://www.stedi.com/pricing) for details.
</Warning>

## Types of MBI lookups

There are two types of MBI lookups you can perform with Stedi. For each, you'll use a special payer ID that tells Stedi to perform an MBI lookup for the patient in addition to a standard eligibility check.

| Type     | What's required                                                    | Payer ID     |
| -------- | ------------------------------------------------------------------ | ------------ |
| With SSN | first name, last name, date of birth, Social Security Number (SSN) | `MBILU`      |
| No SSN   | first name, last name, date of birth, U.S. state                   | `MBILUNOSSN` |

<Note>
  When running an MBI lookup without SSN using our [raw
  X12](/healthcare/api-reference/post-healthcare-eligibility-raw-x12) or
  [SOAP](/healthcare/api-reference/post-healthcare-eligibility-soap) endpoints,
  you must include a city, in addition to a U.S. state, in `Loop 2100C N4`. You
  can use a dummy city value, such as `DUMMY`, if needed. If you omit the city
  value, you'll receive an X12 validation error.
</Note>

We recommend running MBI lookups **with** the patient's SSN whenever possible. When the SSN is present, the MBI lookup has a higher likelihood of successfully returning their MBI. MBI lookups with no SSN are a fallback option when the patient's SSN isn't available.

You don't need to include more patient demographic information than what's required, such as additional address data. It doesn’t improve MBI lookup success rates.

## Transaction enrollment

[Transaction enrollment](/healthcare/transaction-enrollment) is the process of registering a provider to exchange specific healthcare transactions with a payer.

Unlike standard eligibility checks, MBI lookups **always** require transaction enrollment. This is because MBI lookups involve sending requests to special Stedi payers that tell Stedi to perform the MBI lookup in addition to a standard eligibility check. The provider must be enrolled with Stedi's MBI lookup payers to use these services.

To enroll, complete the following steps:

1. Create a provider record with the information required for enrollment. If you already have a record for the provider, you can skip this step. [Stedi portal](https://portal.stedi.com/app/healthcare/providers) | [API endpoint](/healthcare/api-reference/post-enrollment-create-provider)
2. Submit an enrollment request for **Real-time eligibility checks**. [Stedi portal](https://portal.stedi.com/app/healthcare/enrollments) | [API endpoint](/healthcare/api-reference/post-enrollment-create-enrollment)

   Select the payer ID based on the type of MBI lookup you want to perform:

   * **With SSN:** [`MBILU` (CMS MBI Lookup)](https://www.stedi.com/healthcare/network?page=0\&search=MBIL\&entry=ASKVB)
   * **No SSN:** [`MBILUNOSSN` (CMS MBI Lookup Without SSN)](https://www.stedi.com/healthcare/network?page=0\&search=MBIL\&entry=APSMC)

If you want to perform both types of MBI lookups, you must submit separate enrollment requests for each payer ID.

## Run MBI lookups

You can run MBI lookups with and without SSN using the following endpoints:

* [Real-Time Eligibility Check JSON](/healthcare/api-reference/post-healthcare-eligibility)
* [Real-Time Eligibility Check Raw X12](/healthcare/api-reference/post-healthcare-eligibility-raw-x12)
* [Real-Time Eligibility Check SOAP](/healthcare/api-reference/post-healthcare-eligibility-soap)
* [Batch Eligibility Check](/healthcare/api-reference/post-healthcare-batch-eligibility)

You can also run MBI lookups **with SSN** through batch CSV uploads. MBI lookups with no SSN aren't supported for batch CSV.

### Request

Construct an eligibility check request that includes the required patient demographic data:

* **With SSN:** first name, last name, date of birth, Social Security Number (SSN)
* **No SSN:** first name, last name, date of birth, U.S. state

<Note>
  When running an MBI lookup without SSN using our [raw
  X12](/healthcare/api-reference/post-healthcare-eligibility-raw-x12) or
  [SOAP](/healthcare/api-reference/post-healthcare-eligibility-soap) endpoints,
  you must include a city, in addition to a U.S. state, in `Loop 2100C N4`. You
  can use a dummy city value, such as `DUMMY`, if needed. If you omit the city
  value, you'll receive an X12 validation error.
</Note>

Set the `tradingPartnerServiceId` to:

* **With SSN:** `MBILU`
* **No SSN:** `MBILUNOSSN`

These are special payer IDs that tell Stedi to perform an MBI lookup for the patient in addition to a standard eligibility check.

You don't need to include other patient information, such as additional address data. It doesn’t improve lookup success rates.

The following sample requests show how to perform an MBI lookup for a patient named Jane Doe.

{/* schema:EligibilityCheckRequestContent */}

<Tabs items={["With SSN", "No SSN"]}>
  <Tab value="With SSN">
    ```bash Example MBI Lookup request
    curl --request POST \
      --url https://healthcare.us.stedi.com/2024-04-01/change/medicalnetwork/eligibility/v3 \
      --header 'Authorization: <api-key>' \
      --header 'Content-Type: application/json' \
      --data '{
      "tradingPartnerServiceId": "MBILU",
      "externalPatientId": "UAA111222333",
      "encounter": {
        "serviceTypeCodes": [
          "30"
        ]
      },
      "provider": {
        "organizationName": "ACME Health Services",
        "npi": "1999999984"
      },
      "subscriber": {
        "dateOfBirth": "19000101",
        "firstName": "Jane",
        "lastName": "Doe",
        "ssn": "123456789"
      }
    }'
    ```
  </Tab>

  <Tab value="No SSN">
    ```bash Example MBI Lookup request
    curl --request POST \
      --url https://healthcare.us.stedi.com/2024-04-01/change/medicalnetwork/eligibility/v3 \
      --header 'Authorization: <api-key>' \
      --header 'Content-Type: application/json' \
      --data '{
      "tradingPartnerServiceId": "MBILUNOSSN",
      "externalPatientId": "UAA111222333",
      "encounter": {
        "serviceTypeCodes": [
          "30"
        ]
      },
      "provider": {
        "organizationName": "ACME Health Services",
        "npi": "1999999984"
      },
      "subscriber": {
        "dateOfBirth": "19000101",
        "firstName": "Jane",
        "lastName": "Doe",
        "address": {
          "state": "WV"
        }
      }
    }'
    ```
  </Tab>
</Tabs>

### Response

Stedi uses the patient’s demographic data and SSN to perform an MBI lookup. If there is a match, Stedi submits an eligibility check to CMS. The response shape is the same for both the SSN and no SSN lookup types.

Stedi returns a complete eligibility response from CMS for the patient and places the patient's MBI in the `subscriber.memberId` property.
Visit [Determine patient benefits](/healthcare/eligibility-active-coverage-benefits) for details about how you can use the eligibility response to determine a patient's coverage status and benefits.

The following example shows a CMS eligibility response returned from an MBI lookup. In this scenario, the patient's MBI is `1AA2CC3DD45`.

{/* schema:EligibilityCheckResponseContent */}

```json Example MBI Lookup response
{
  "meta": {
    "senderId": "STEDI",
    "submitterId": "117151744",
    "applicationMode": "production",
    "traceId": "11112222333344445555666677",
    "outboundTraceId": "11112222333344445555666677"
  },
  "controlNumber": "112233445",
  "id": "ec_01234567-89ab-cdef-0123-456789abcdef",
  "reassociationKey": "112233445",
  "tradingPartnerServiceId": "CMS",
  "provider": {
    "providerName": "ACME HEALTH SERVICES",
    "entityIdentifier": "Provider",
    "entityType": "Non-Person Entity",
    "npi": "1999999984"
  },
  "subscriber": {
    "memberId": "1AA2CC3DD45",
    "firstName": "JANE",
    "lastName": "DOE",
    "middleName": "A",
    "gender": "F",
    "entityIdentifier": "Insured or Subscriber",
    "entityType": "Person",
    "dateOfBirth": "19000101",
    "address": {
      "address1": "1234 FIRST ST",
      "city": "NEW YORK",
      "state": "WV",
      "postalCode": "123451111"
    }
  },
  "payer": {
    "entityIdentifier": "Payer",
    "entityType": "Non-Person Entity",
    "name": "CMS",
    "payorIdentification": "CMS"
  },
  "planDateInformation": {
    "eligibility": "20241025"
  },
  "planStatus": [
    {
      "statusCode": "1",
      "status": "Active Coverage",
      "serviceTypeCodes": ["88"]
    },
    {
      "statusCode": "1",
      "status": "Active Coverage",
      "serviceTypeCodes": [
        "30",
        "42",
        "45",
        "48",
        "49",
        "69",
        "76",
        "83",
        "A5",
        "A7",
        "AG",
        "BT",
        "BU",
        "BV"
      ]
    },
    {
      "statusCode": "1",
      "status": "Active Coverage",
      "serviceTypeCodes": [
        "30",
        "2",
        "23",
        "24",
        "25",
        "26",
        "27",
        "28",
        "3",
        "33",
        "36",
        "37",
        "38",
        "39",
        "40",
        "42",
        "50",
        "51",
        "52",
        "53",
        "67",
        "69",
        "73",
        "76",
        "83",
        "86",
        "98",
        "A4",
        "A6",
        "A8",
        "AI",
        "AJ",
        "AK",
        "AL",
        "BT",
        "BU",
        "BV",
        "DM",
        "UC"
      ]
    }
  ],
  "benefitsInformation": [
    {
      "code": "I",
      "name": "Non-Covered",
      "serviceTypeCodes": ["41", "54"],
      "serviceTypes": ["Routine (Preventive) Dental", "Long Term Care"],
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable"
    },
    {
      "code": "1",
      "name": "Active Coverage",
      "serviceTypeCodes": ["88"],
      "serviceTypes": ["Pharmacy"],
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable"
    },
    {
      "code": "R",
      "name": "Other or Additional Payor",
      "insuranceTypeCode": "QM",
      "insuranceType": "Qualified Medicare Beneficiary",
      "planCoverage": "CA QMB Plan",
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable",
      "benefitsDateInformation": {
        "coordinationOfBenefits": "20230101"
      }
    },
    {
      "code": "1",
      "name": "Active Coverage",
      "serviceTypeCodes": [
        "30",
        "42",
        "45",
        "48",
        "49",
        "69",
        "76",
        "83",
        "A5",
        "A7",
        "AG",
        "BT",
        "BU",
        "BV"
      ],
      "serviceTypes": [
        "Health Benefit Plan Coverage",
        "Home Health Care",
        "Hospice",
        "Hospital - Inpatient",
        "Hospital - Room and Board",
        "Maternity",
        "Dialysis",
        "Infertility",
        "Psychiatric - Room and Board",
        "Psychiatric - Inpatient",
        "Skilled Nursing Care",
        "Gynecological",
        "Obstetrical",
        "Obstetrical/Gynecological"
      ],
      "insuranceTypeCode": "MA",
      "insuranceType": "Medicare Part A",
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable",
      "benefitsDateInformation": {
        "plan": "20190101"
      },
      "additionalInformation": [
        {
          "description": "0-Beneficiary insured due to age OASI"
        }
      ]
    },
    {
      "code": "C",
      "name": "Deductible",
      "serviceTypeCodes": ["30"],
      "serviceTypes": ["Health Benefit Plan Coverage"],
      "insuranceTypeCode": "QM",
      "insuranceType": "Qualified Medicare Beneficiary",
      "planCoverage": "Medicare Part A",
      "timeQualifierCode": "26",
      "timeQualifier": "Episode",
      "benefitAmount": "0",
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable",
      "benefitsDateInformation": {
        "plan": "20240101-20241231"
      }
    },
    {
      "code": "1",
      "name": "Active Coverage",
      "serviceTypeCodes": [
        "30",
        "2",
        "23",
        "24",
        "25",
        "26",
        "27",
        "28",
        "3",
        "33",
        "36",
        "37",
        "38",
        "39",
        "40",
        "42",
        "50",
        "51",
        "52",
        "53",
        "67",
        "69",
        "73",
        "76",
        "83",
        "86",
        "98",
        "A4",
        "A6",
        "A8",
        "AI",
        "AJ",
        "AK",
        "AL",
        "BT",
        "BU",
        "BV",
        "DM",
        "UC"
      ],
      "serviceTypes": [
        "Health Benefit Plan Coverage",
        "Surgical",
        "Diagnostic Dental",
        "Periodontics",
        "Restorative",
        "Endodontics",
        "Maxillofacial Prosthetics",
        "Adjunctive Dental Services",
        "Consultation",
        "Chiropractic",
        "Dental Crowns",
        "Dental Accident",
        "Orthodontics",
        "Prosthodontics",
        "Oral Surgery",
        "Home Health Care",
        "Hospital - Outpatient",
        "Hospital - Emergency Accident",
        "Hospital - Emergency Medical",
        "Hospital - Ambulatory Surgical",
        "Smoking Cessation",
        "Maternity",
        "Diagnostic Medical",
        "Dialysis",
        "Infertility",
        "Emergency Services",
        "Professional (Physician) Visit - Office",
        "Psychiatric",
        "Psychotherapy",
        "Psychiatric - Outpatient",
        "Substance Abuse",
        "Alcoholism",
        "Drug Addiction",
        "Vision (Optometry)",
        "Gynecological",
        "Obstetrical",
        "Obstetrical/Gynecological",
        "Durable Medical Equipment",
        "Urgent Care"
      ],
      "insuranceTypeCode": "MB",
      "insuranceType": "Medicare Part B",
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable",
      "benefitsDateInformation": {
        "plan": "20190101"
      },
      "additionalInformation": [
        {
          "description": "0-Beneficiary insured due to age OASI"
        }
      ]
    },
    {
      "code": "C",
      "name": "Deductible",
      "serviceTypeCodes": ["30"],
      "serviceTypes": ["Health Benefit Plan Coverage"],
      "insuranceTypeCode": "QM",
      "insuranceType": "Qualified Medicare Beneficiary",
      "planCoverage": "Medicare Part B",
      "timeQualifierCode": "23",
      "timeQualifier": "Calendar Year",
      "benefitAmount": "0",
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable",
      "benefitsDateInformation": {
        "plan": "20240101-20241231"
      }
    },
    {
      "code": "A",
      "name": "Co-Insurance",
      "serviceTypeCodes": ["30"],
      "serviceTypes": ["Health Benefit Plan Coverage"],
      "insuranceTypeCode": "QM",
      "insuranceType": "Qualified Medicare Beneficiary",
      "planCoverage": "Medicare Part B",
      "timeQualifierCode": "27",
      "timeQualifier": "Visit",
      "benefitPercent": "0",
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable",
      "benefitsDateInformation": {
        "plan": "20240101-20241231"
      }
    },
    {
      "code": "R",
      "name": "Other or Additional Payor",
      "serviceTypeCodes": ["88"],
      "serviceTypes": ["Pharmacy"],
      "insuranceTypeCode": "OT",
      "insuranceType": "Other",
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable",
      "benefitsAdditionalInformation": {
        "planNumber": "A0505",
        "planNetworkIdNumber": "555"
      },
      "benefitsDateInformation": {
        "benefit": "20230101"
      },
      "benefitsRelatedEntity": {
        "entityIdentifier": "Payer",
        "entityType": "Non-Person Entity",
        "entityName": "UHC OF CALIFORNIA",
        "address": {
          "address1": "202 Main St",
          "city": "Sacramento",
          "state": "CA",
          "postalCode": "94203"
        },
        "contactInformation": {
          "contacts": [
            {
              "communicationMode": "Telephone",
              "communicationNumber": "8006446644"
            },
            {
              "communicationMode": "Uniform Resource Locator (URL)",
              "communicationNumber": "UHC.com/Medicare"
            }
          ]
        }
      },
      "benefitsRelatedEntities": [
        {
          "entityIdentifier": "Payer",
          "entityType": "Non-Person Entity",
          "entityName": "UHC OF CALIFORNIA",
          "address": {
            "address1": "202 Main St",
            "city": "Sacramento",
            "state": "CA",
            "postalCode": "94203"
          },
          "contactInformation": {
            "contacts": [
              {
                "communicationMode": "Telephone",
                "communicationNumber": "8006446644"
              },
              {
                "communicationMode": "Uniform Resource Locator (URL)",
                "communicationNumber": "UHC.com/Medicare"
              }
            ]
          }
        }
      ]
    },
    {
      "code": "U",
      "name": "Contact Following Entity for Eligibility or Benefit Information",
      "serviceTypeCodes": ["30"],
      "serviceTypes": ["Health Benefit Plan Coverage"],
      "insuranceTypeCode": "HN",
      "insuranceType": "Health Maintenance Organization (HMO) - Medicare Risk",
      "inPlanNetworkIndicatorCode": "W",
      "inPlanNetworkIndicator": "Not Applicable",
      "benefitsAdditionalInformation": {
        "planNumber": "A0505",
        "planNetworkIdNumber": "555"
      },
      "benefitsDateInformation": {
        "coordinationOfBenefits": "20230101"
      },
      "benefitsRelatedEntity": {
        "entityIdentifier": "Primary Payer",
        "entityType": "Non-Person Entity",
        "entityName": "UHC OF CALIFORNIA",
        "address": {
          "address1": "202 Main St",
          "city": "Sacramento",
          "state": "CA",
          "postalCode": "94203"
        },
        "contactInformation": {
          "contacts": [
            {
              "communicationMode": "Telephone",
              "communicationNumber": "8006446644"
            },
            {
              "communicationMode": "Uniform Resource Locator (URL)",
              "communicationNumber": "UHC.com/Medicare"
            }
          ]
        }
      },
      "benefitsRelatedEntities": [
        {
          "entityIdentifier": "Primary Payer",
          "entityType": "Non-Person Entity",
          "entityName": "UHC OF CALIFORNIA",
          "address": {
            "address1": "202 Main St",
            "city": "Sacramento",
            "state": "CA",
            "postalCode": "94203"
          },
          "contactInformation": {
            "contacts": [
              {
                "communicationMode": "Telephone",
                "communicationNumber": "8006446644"
              },
              {
                "communicationMode": "Uniform Resource Locator (URL)",
                "communicationNumber": "UHC.com/Medicare"
              }
            ]
          }
        }
      ],
      "additionalInformation": [
        {
          "description": "MA Bill Option Code - A"
        }
      ]
    }
  ],
  "errors": [],
  "x12": ""
}
```

### Concurrency limit

MBI lookups you perform using real-time eligibility check endpoints (JSON and Raw X12) share a concurrency pool with other real-time healthcare APIs. For more information, visit [Concurrency limits](/healthcare/api-reference#concurrency-limits).

MBI lookups you perform using the [Batch Eligibility Check](/healthcare/api-reference/post-healthcare-batch-eligibility) endpoint don't count toward your Stedi account concurrency limit.

## Mock request

When you submit the following mock MBI lookup request to the [Real-Time Eligibility Check](/healthcare/api-reference/post-healthcare-eligibility) endpoint with a [test API key](/healthcare/api-reference#api-key-types), Stedi returns mock benefits data you can use for testing.

This mock request is for an MBI lookup with SSN.

<Tip>
  Mock requests are free for testing purposes and won't incur any charges in
  your Stedi account.
</Tip>

Request Notes:

* `encounter`: Only service type code 30 is supported.
* `provider`: You can use any organization name and any NPI, as long as it passes check digit validation. To generate a dummy NPI, you can use this [free tool](https://jsfiddle.net/alexdresko/cLNB6).
* `subscriber`: You must use the exact values in the test request. Other birth dates, first names, last names, and Social Security Numbers return errors.

<Accordion title="MBI lookup mock request">
  {/* schema:EligibilityCheckRequestContent */}

  ```bash
  curl --request POST \
    --url 'https://healthcare.us.stedi.com/2024-04-01/change/medicalnetwork/eligibility/v3' \
    --header 'Authorization: Key <test_api_key>' \
    --header 'Content-Type: application/json' \
    --data '{
      "controlNumber": "112233445",
      "tradingPartnerServiceId": "MBILU",
      "provider": {
          "organizationName": "Provider Name",
          "npi": "1999999984"
      },
      "subscriber": {
          "lastName": "Doe",
          "dateOfBirth": "19550505",
          "ssn": "123456789"
      },
      "encounter": {
          "serviceTypeCodes": [
              "30"
          ]
      }
  }'
  ```
</Accordion>

## Health Insurance Claim Number (HICN)

Some payers return the patient's MBI in one of the following properties of the standard eligibility response:

* [`benefitsInformation.benefitsAdditionalInformation.hicNumber`](/healthcare/api-reference/post-healthcare-eligibility#response.benefitsInformation.benefitsAdditionalInformation.hicNumber)
* [`planInformation.hicNumber`](/healthcare/api-reference/post-healthcare-eligibility#response.planInformation.hicNumber)

If the value in either of these properties matches the format specified in the [Medicare Beneficiary Identifier documentation](https://www.cms.gov/training-education/partner-outreach-resources/new-medicare-card/medical-beneficiary-identifiers-mbis), the number is likely an MBI. In these cases, you don't need to perform an MBI lookup - you can use this value in a standard eligibility check to CMS.

You're most likely to receive an MBI in eligibility responses from commercial Medicare Advantage plans, but they can also be present in responses from Medicaid plans for dual-eligible patients.

## Medicare Advantage plans

A Medicare Advantage plan (also known as Medicare Part C) is a type of health insurance plan offered by private companies that contract with Medicare to provide all of a patient's Part A (hospital insurance) and Part B (medical insurance) benefits.

Medicare Advantage plans have their own unique member ID, which **isn't** returned in the MBI lookup response. You also shouldn't submit eligibility checks for Medicare Advantage plans to CMS (HETS) - you should submit them to the actual Medicare Advantage plan payer instead.

However, you can use MBI lookups to determine a patient's Medicare Advantage payer. If available, the MBI lookup response will include the patient's Medicare Advantage plan name in the [`benefitsInformation.benefitsRelatedEntities.entityName`](/healthcare/api-reference/post-healthcare-eligibility#response.benefitsInformation.benefitsRelatedEntities.entityName) property.

Many Medicare Advantage plans allow you to submit [eligibility checks](/healthcare/send-eligibility-checks) with just the patient's name and date of birth. However, if that approach is unsuccessful and you don't have the patient's member ID, you can use [Insurance Discovery](/healthcare/insurance-discovery) to retrieve benefits information with the patient's demographic information instead.

## Recommended retry strategy

Implementing the right retry strategy for eligibility check failures saves a lot of time and money.

At a minimum, we **strongly recommend** automatically retrying every request that fails due to payer connectivity issues. Automatic retries resolve a significant portion of these types of failures without manual intervention. Visit [Retry strategy](/healthcare/eligibility-troubleshooting#retry-strategy) for details.