Prerequisites

Before making your first eligibility request, you need:

1. Optum Developer Account — Register at developer.optum.com
2. Application credentials — Create an application in the developer portal to receive your client_id and client_secret
3. Eligibility API access — Request access from the Marketplace

Step 1: Get an Access Token

The Eligibility API uses OAuth 2.0 client credentials flow.

curl -X POST https://api.optum.com/oauth/token \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "grant_type=client_credentials" \
  -d "client_id=$CLIENT_ID" \
  -d "client_secret=$CLIENT_SECRET" \
  -d "scope=eligibility:read"

Response:

{
  "access_token": "eyJhbGciOiJSUzI1...",
  "token_type": "Bearer",
  "expires_in": 3600
}

Step 2: Submit Your First Inquiry

curl -X POST https://sandbox-apigw.optum.com/eligibility/v3/inquiry \
  -H "Authorization: Bearer $ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "memberId": "U12345678",
    "dateOfService": "2026-01-15",
    "providerNpi": "1234567890",
    "serviceType": "30"
  }'

Step 3: Interpret the Response

A successful response returns:

{
  "transactionId": "TXN-20260115-001",
  "memberId": "U12345678",
  "coverageActive": true,
  "deductible": 1500.00,
  "deductibleMet": 450.00,
  "copay": 30.00,
  "outOfPocketMax": 5000.00,
  "outOfPocketMet": 780.00
}

coverageActive: true means the member has active coverage for the requested service type.

Next Steps

• Explore all request parameters in the API Reference
• Learn about error codes and retry strategies
• Set up sandbox testing credentials