The coordination of benefits (COB) response includes information about the patient’s active health plans, subscriber information, and coordination of benefits. Unlike standard eligibility checks, the COB response shape is standardized across all supported payers. There are no payer-specific variations in what information is included or how the response is structured.

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COB status

The coordinationOfBenefits object contains status information about whether a COB instance exists and whether Stedi was able to determine the primary payer. 
"coordinationOfBenefits": {
    "classification": "CobInstanceExistsPrimacyDetermined",
    "instanceExists": true,
    "primacyDetermined": true,
    "coverageOverlap": true,
    "benefitOverlap": true
  }
A COB check response can have one of the following statuses, indicated by the coordinationOfBenefits.classification property.
statusDescription
MemberFoundNoCobThe patient has coverage with the payer you checked, but Stedi didn’t find any other health plans with overlapping coverage. Note that Stedi can only report information for other COB-supported health plans from our payer list. For example, if the individual has coverage from Cigna and Medicare, a COB check to Cigna will state that no COB was detected, since Medicare is not a supported payer. You can find a complete list of supported payers for COB checks in the Payer Network.
CoverageOverlapNoBenefitOverlapThe patient has overlapping coverage with at least one other health plan, but there is no benefit overlap between the plans. Coordination of benefits is not required.
CoverageOverlapExistsNotSubjectToCobThe patient has overlapping coverage with at least one other health plan, but coordination of benefits is not required.
CobInstanceExistsPrimacyUndeterminedThe patient has overlapping coverage with at least one other health plan and coordination of benefits is required. However, Stedi could not determine the primary payer. We recommend contacting the patient’s health plans for further guidance.
CobInstanceExistsPrimacyDeterminedThe patient has overlapping coverage with at least one other health plan, and Stedi was able to identify the primary payer.

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Payer primacy

The response includes a benefitsInformation object with code = R when Stedi finds overlapping coverage with another health plan. The benefitsInformation.benefitsRelatedEntities object contains information about the other payer, and the entityIdentifier property indicates the payer’s primacy for payment on claims when this information is available. It can be set to:
  • Payer: Stedi didn’t find a COB instance or could not determine primacy.
  • Primary Payer: This payer is the primary payer for the service type.
  • Secondary Payer: This payer is the secondary payer for the service type.
  • Tertiary Payer: This payer is the tertiary payer for the service type.
In the following example, the patient has overlapping coverage for medical care services with Cigna, the primary payer for medical care services. 
{
      "code": "R",
      "name": "Other or Additional Payor",
      "serviceTypeCodes": [
        "1"
      ],
      "serviceTypes": [
        "Medical Care"
      ],
      "benefitsDateInformation": {
        "coordinationOfBenefits": "2024-07-01"
      },
      "benefitsRelatedEntities": [
        {
          "entityIdentifier": "Primary Payer",
          "entityName": "CIGNA",
          "entityIdentification": "PI",
          "entityIdentificationValue": "1006"
        },
        {
          "entityIdentifier": "Insured or Subscriber",
          "entityFirstname": "JOHN",
          "entityMiddlename": "X",
          "entityIdentification": "MI",
          "entityIdentificationValue": "00000000000",
          "entityLastname": "DOE"
        }
      ],
      "subscriber": {
        "dateOfBirth": "2002-12-31"
      }
    }
When Stedi can’t reliably determine primacy, you should contact the patient’s health plans directly for further guidance.

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Primacy rules

Medicare and Medicare Advantage plans are not supported, so these plans aren’t included in the primacy determination process.
Our COB service follows the guidelines set by the National Association of Insurance Commissioners (NAIC) to determine payer primacy. You may also want to refer to these guidelines when submitting claims.

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Plan responsibilities

In almost all cases, the primary plan pays benefits first as if no other plan exists. The one exception to this policy is when the patient has both an HMO (closed network plan) and a PPO (open network plan). When the HMO is the primary plan and the PPO is secondary, the PPO will pay first when the patient uses out-of-network providers unless it’s an emergency or an authorized referral covered by the HMO. When multiple policies are treated as a single plan, the primacy determination applies to the entire plan. The plans must coordinate amongst themselves according to their contracts. If more than one insurance company provides benefits under the plan, the one designated as primary is responsible for complying with coordination of benefits rules.

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Order of benefits rules

After the primary plan pays, each subsequent plan pays remaining eligible costs. Each health plan determines their order of benefits using the first of the following rules that apply: 1. Non-Dependent vs. Dependent vs. Medicare
  • A plan covering the patient as an employee, subscriber, or retiree is primary over a plan that covers them as a dependent.
  • If the patient also has Medicare, special rules apply:
    • Medicare is secondary to a plan covering the person as a dependent.
    • Medicare is primary to a plan covering the person as an employee (from an employer with more than 20 employees), subscriber, or retiree.
    • If the patient has all three plan types, the order of primacy is: Medicare, then the plan covering the person as a dependent, and then any other plans.
2. Dependent child with multiple plans Note that the following rules are the same regardless of whether the subscribers of the multiple plans are the child’s parents or other significant individuals in their life (not their parents).
  • If the two subscribers are married or living together: The subscriber with the birthday that occurs first in the calendar year has the primary plan. If both subscribers have the same birthday, the plan that has covered the child the longest is primary.
  • If the dependent child’s coverage under the spouse’s plan began on the same date as their coverage under either or both parents’ plans, the order of benefits will be determined using the birthday rule.
  • If the two subscribers are divorced, separated, or not living together, a court order typically decides which plan is primary. Otherwise:
    • The plan of the custodial parent is primary.
    • The plan of the spouse of the custodial parent is secondary.
    • The plan of the non-custodial parent is tertiary.
    • The plan of the spouse of the non-custodial parent is last.
  • If a dependent child has coverage under either or both parents’ plans and is also covered as a dependent under a spouse’s plan, apply rule 5 - Length of coverage.
3. Active vs. retired employees Coverage from a current employer (active employee) is primary to retired or laid-off employee plans. 4. COBRA vs. state continuation coverage Employer-based plans are primary to COBRA coverage. 5. Length of coverage If other rules don’t decide, the plan covering the person for the longest time is primary. 6. Final rule (If no other rules apply) If no clear primary plan is determined, costs are split equally between the plans.

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Sample response interpretation

The following example COB response shows information for a dependent who is covered by multiple health plans through their parents’ policies. The COB check was submitted to Aetna with a service type code of 30 and a date of service of 2024-11-27. The response indicates the following:
  • Active coverage: The patient has active coverage with Aetna for medical care services, pharmacy services, and vision services. This is indicated by the three objects in the benefitsInformation array with the code set to 1.
  • Coverage overlap: The patient has overlapping coverage for medical care services between two health plans. This is indicated by the benefitsInformation object with the code set to R.
  • Primacy: The other health plan is Cigna, listed in benefitsInformation.benefitsRelatedEntities. Cigna is the primary payer for medical care services. Note that the ID returned in this property is proprietary to our COB check product, so you can’t use it as the Payer ID for eligibility checks or other API requests to Stedi. It likely doesn’t match the Payer IDs listed in the Payer Network.
  • COB instance: There is a COB instance for medical care services on the date of service provided in the request. This is indicated in the coordinationOfBenefits object.
Based on this response, you must send claims first to Cigna as the primary payer for medical care services. Once Cigna adjudicates the claim, you can send another one, if necessary, to Aetna as the secondary payer (subject to specific payer claims processing rules). Before sending claims we’d also recommend sending a separate eligibility check to Aetna to verify coverage status. 
{
  "benefitsInformation": [
    {
      "code": "1",
      "name": "Active Coverage",
      "serviceTypeCodes": [
        "1"
      ],
      "serviceTypes": [
        "Medical Care"
      ],
      "benefitsDateInformation": {
        "benefitBegin": "2023-03-01"
      },
      "subscriber": {
        "dateOfBirth": "2002-02-27"
      }
    },
    {
      "code": "1",
      "name": "Active Coverage",
      "serviceTypeCodes": [
        "88"
      ],
      "serviceTypes": [
        "Pharmacy"
      ],
      "benefitsDateInformation": {
        "benefitBegin": "2023-03-01"
      },
      "subscriber": {
        "dateOfBirth": "2002-02-27"
      }
    },
    {
      "code": "1",
      "name": "Active Coverage",
      "serviceTypeCodes": [
        "AL"
      ],
      "serviceTypes": [
        "Vision (Optometry)"
      ],
      "benefitsDateInformation": {
        "benefitBegin": "2023-03-01"
      },
      "subscriber": {
        "dateOfBirth": "2002-02-27"
      }
    },
    {
      "code": "R",
      "name": "Other or Additional Payor",
      "serviceTypeCodes": [
        "1"
      ],
      "serviceTypes": [
        "Medical Care"
      ],
      "benefitsDateInformation": {
        "coordinationOfBenefits": "2024-07-01"
      },
      "benefitsRelatedEntities": [
        {
          "entityIdentifier": "Primary Payer",
          "entityName": "CIGNA",
          "entityIdentification": "PI",
          "entityIdentificationValue": "1006"
        },
        {
          "entityIdentifier": "Insured or Subscriber",
          "entityFirstname": "JOHN",
          "entityMiddlename": "X",
          "entityIdentification": "MI",
          "entityIdentificationValue": "00000000000",
          "entityLastname": "DOE"
        }
      ],
      "subscriber": {
        "dateOfBirth": "2002-12-31"
      }
    }
  ],
  "coordinationOfBenefits": {
    "classification": "CobInstanceExistsPrimacyDetermined",
    "instanceExists": true,
    "primacyDetermined": true,
    "coverageOverlap": true,
    "benefitOverlap": true
  },
  "dependent": {
    "firstName": "JORDAN",
    "lastName": "DOE",
    "gender": "M",
    "dateOfBirth": "2002-12-31",
    "relationToSubscriber": "Child",
    "relationToSubscriberCode": "19",
    "address": {
      "address1": "1 MAIN ST.",
      "city": "NEW YORK",
      "state": "NY",
      "postalCode": "10000"
    }
  },
  "errors": [],
  "meta": {
    "applicationMode": "production",
    "traceId": "01JDQFT4W3KTWZNTADEZ55BFFX",
    "outboundTraceId": "01JDQFT4W3KTWZNTADEZ55BFFX"
  },
  "payer": {
    "name": "Aetna",
    "payerIdentification": "AETNA-USH"
  },
  "provider": {
    "providerOrgName": "AETNA-USH",
    "npi": "1999999984"
  },
  "subscriber": {
    "memberId": "W000000000",
    "firstName": "JOHN",
    "lastName": "DOE",
    "address": {
      "address1": "1 MAIN ST.",
      "city": "NEW YORK",
      "state": "NY",
      "postalCode": "10000"
    }
  }
}

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Request and response examples

The following examples show request and response data for common COB scenarios.

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COB exists, primacy determined

In the following example, the COB check was submitted to Cigna with a service type code of 30 and a date of service of 2024-12-19. The response indicates that the patient has active coverage with Cigna for medical care services, and that there is overlapping coverage with Kaiser Foundation Health Plan of Massachusetts. COB is required for medical care services, and Kaiser is the primary payer.

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Coverage overlap, no benefit overlap

In the following example, the COB check was submitted to Cigna with a service type code of 30 and a date of service of 2025-01-01. The response indicates that the patient has active coverage with Cigna for medical care services, and that there is overlapping coverage with Aetna for dental care services. There is no benefit overlap between the two health plans because dental and medical benefits have two different service type codes. COB is not required.

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Member found, no COB

In the following example, the COB check was submitted to UnitedHealthcare with a service type code of 30 and a date of service of 2023-01-10. The response indicates that the patient has active coverage with UnitedHealthcare for medical care services, but there is no overlapping coverage with any other health plan.

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Follow up with eligibility checks

Our COB data is updated weekly, and the response doesn’t contain complete details about the patient’s coverage with each health plan. When Stedi finds overlapping coverage, we strongly recommend conducting follow-up eligibility checks with each payer to verify coverage status and retrieve the patient’s complete, up-to-date benefits information.