Coordination of benefits

COB assigns an order for claim processing

The CMS Uniform Glossary supplies general health-coverage terms, while the HealthCare.gov glossary offers consumer orientation. The member's plans and applicable coordination rules establish the actual processing order.

The primary payer processes the claim first. A secondary payer may then process eligible remaining amounts using information from the primary adjudication. Secondary coverage rarely means every balance will be paid. Deductibles, coinsurance, exclusions, network rules, authorization, coding, and nonduplication rules can still apply.

More coverage does not create one combined plan

Each plan answers its own questions:

• Was the person eligible on the service date?
• Is ABA a covered benefit under this product?
• Is the provider enrolled, contracted, or otherwise payable through the chosen route?
• Was authorization required and effective for the service?
• Did the claim use the required provider, code, modifier, unit, place, and timely-filing information?
• What did the prior payer allow, pay, deny, or assign to the member?

The primary plan's authorization supplies no authorization for the secondary plan. A provider directory entry, eligibility response, or member card also cannot determine payer order by itself.

Keep coverage order and evidence current

At intake and relevant rechecks, ask about all health coverage and record:

• plan and product names, member and group identifiers, and effective dates
• subscriber relationships and other facts the plans request
• each plan's stated primary or secondary position and source date
• COB questionnaires, portal messages, call references, and written decisions
• authorization status for each payer
• claim-submission and crossover route
• family updates involving employment, marriage, divorce, birth, adoption, custody, Medicare, Medicaid, or another coverage change

Route any conflicting payer answers to the designated benefits or payer specialist. A staff guess can send claims in the wrong order and create denials, refunds, or long delays.

When two payers each say the other should process first, ask both for the source and facts behind their position. Confirm the subscriber relationship, employment state, effective dates, dependent status, and any questionnaire still pending. Send only the information allowed through the approved route. Keep the claim on a visible hold until the order is resolved instead of cycling the same transaction between payers.

Medicare illustrates the concept without setting every plan's rule

The CMS Medicare COB page explains that coordination determines which coverage has primary responsibility and how other plans may contribute. It also describes Medicare data exchange and crossover processes.

That page is specific to Medicare coordination. Employer plans, Medicaid, CHIP, Marketplace coverage, liability coverage, and other combinations can follow different laws and plan terms. Use the responsible program's current primary source for the exact member.

CMS also describes the electronic coordination-of-benefits transaction. A secondary claim can carry adjudication information from a prior payer. Transaction capability is a transport rule. It supplies no guarantee that the secondary payer will cover or pay the service.

A fictional two-plan claim

Omar is a fictional parent whose child has two health plans. Both plans confirm in writing that Plan A is primary and Plan B is secondary for the current period. The ABA provider obtains the required authorization from each plan before the relevant services.

For one claim, Plan A allows $300, pays $210, and assigns $90 to the member. The provider then submits the primary adjudication information through Plan B's required route. Plan B allows $270 under its own terms and pays $40. The remaining processed member balance is $90 − $40 = $50.

The $50 result belongs to this example. It cannot be predicted merely by subtracting the first payment from the provider's charge. Both plans' EOBs and the provider ledger need to reconcile.

Track the full COB worklist

A useful worklist separates coverage-order verification, primary claim submission, primary adjudication, secondary submission, secondary adjudication, payment posting, member balance, refund or recoupment, and final reconciliation.

Useful measures include records with current order evidence; primary claims processed; secondary claims submitted by target; matched primary adjudication received; fully reconciled episodes; and unresolved COB cases by age. Keep claims waiting on family, payer, provider, or system action visible with a named owner.

Families can ask which plan the provider will bill first, whether each payer requires its own authorization, how primary EOB information reaches the secondary plan, and when a remaining balance becomes final. Give updates in the family's requested accessible format and explain which step remains open.

Reconcile payer order against current enrollment and the governing COB rules before every corrected or secondary claim. Preserve the primary EOB or remittance, other-coverage record, crossover status, timely-filing evidence, and secondary response. A changed employer, birthday-rule fact, Medicare status, or court order can require a new determination.