Introducing MBI lookups without an SSN

Dec 3, 2025

You can now look up a patient’s Medicare Beneficiary Identifier (MBI) without a Social Security Number (SSN) using Stedi's Eligibility APIs or the Stedi portal.

Two types of MBI lookups
With this update, you can now perform an MBI lookup in two ways. Each uses a different payer ID:

Type

Payer ID

Required patient data

MBI lookup with SSN

MBILU

First name, last name, date of birth, SSN

MBI lookup without SSN

MBILUNOSSN

First name, last name, date of birth, U.S. state

Note: When running an MBI lookup without SSN using our raw X12 or SOAP eligibility 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.

Transaction enrollment
Before running an MBI lookup without an SSN, enroll the provider for eligibility checks with the MBILUNOSSN payer ID using the Transaction Enrollment API or the Stedi portal. Enrollments for the MBILUNOSSN payer typically take 1-3 business days to complete.

You’ll get an email once the enrollment is live. You can also check enrollment status using the List Enrollments or Retrieve Enrollment API endpoints.

Run an MBI lookup without an SSN

After the enrollment is live, send an eligibility check to MBILUNOSSN. Include:

  • The provider’s NPI

  • The patient’s first name

  • The patient’s last name

  • The patient’s date of birth

  • The patient’s U.S. state

  • The patient's city (if using the raw X12 or SOAP eligibility endpoints)

For example, using Stedi’s JSON Eligibility API:

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": "NY"
    }
  }
}'

The response includes the MBI as the subscriber’s member ID. For example:

{
  "subscriber": {
    "memberId": "1AA2CC3DD45",
    "firstName": "JANE",
    "lastName": "DOE",
    ...
    "address": {
      "state": "NY",
      ...
    }
  },
  ...
}

For more details, see our announcement blog.

You can now look up a patient’s Medicare Beneficiary Identifier (MBI) without a Social Security Number (SSN) using Stedi's Eligibility APIs or the Stedi portal.

Two types of MBI lookups
With this update, you can now perform an MBI lookup in two ways. Each uses a different payer ID:

Type

Payer ID

Required patient data

MBI lookup with SSN

MBILU

First name, last name, date of birth, SSN

MBI lookup without SSN

MBILUNOSSN

First name, last name, date of birth, U.S. state

Note: When running an MBI lookup without SSN using our raw X12 or SOAP eligibility 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.

Transaction enrollment
Before running an MBI lookup without an SSN, enroll the provider for eligibility checks with the MBILUNOSSN payer ID using the Transaction Enrollment API or the Stedi portal. Enrollments for the MBILUNOSSN payer typically take 1-3 business days to complete.

You’ll get an email once the enrollment is live. You can also check enrollment status using the List Enrollments or Retrieve Enrollment API endpoints.

Run an MBI lookup without an SSN

After the enrollment is live, send an eligibility check to MBILUNOSSN. Include:

  • The provider’s NPI

  • The patient’s first name

  • The patient’s last name

  • The patient’s date of birth

  • The patient’s U.S. state

  • The patient's city (if using the raw X12 or SOAP eligibility endpoints)

For example, using Stedi’s JSON Eligibility API:

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": "NY"
    }
  }
}'

The response includes the MBI as the subscriber’s member ID. For example:

{
  "subscriber": {
    "memberId": "1AA2CC3DD45",
    "firstName": "JANE",
    "lastName": "DOE",
    ...
    "address": {
      "state": "NY",
      ...
    }
  },
  ...
}

For more details, see our announcement blog.

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Stedi is a registered trademark of Stedi, Inc. All names, logos, and brands of third parties listed on our site are trademarks of their respective owners (including “X12”, which is a trademark of X12 Incorporated). Stedi, Inc. and its products and services are not endorsed by, sponsored by, or affiliated with these third parties. Our use of these names, logos, and brands is for identification purposes only, and does not imply any such endorsement, sponsorship, or affiliation.

Get updates on what’s new at Stedi

Backed by

Stedi is a registered trademark of Stedi, Inc. All names, logos, and brands of third parties listed on our site are trademarks of their respective owners (including “X12”, which is a trademark of X12 Incorporated). Stedi, Inc. and its products and services are not endorsed by, sponsored by, or affiliated with these third parties. Our use of these names, logos, and brands is for identification purposes only, and does not imply any such endorsement, sponsorship, or affiliation.

Get updates on what’s new at Stedi

Backed by

Stedi is a registered trademark of Stedi, Inc. All names, logos, and brands of third parties listed on our site are trademarks of their respective owners (including “X12”, which is a trademark of X12 Incorporated). Stedi, Inc. and its products and services are not endorsed by, sponsored by, or affiliated with these third parties. Our use of these names, logos, and brands is for identification purposes only, and does not imply any such endorsement, sponsorship, or affiliation.