2.6 Commercial Insurance & Coordination of Benefits (COB)
Key Takeaways
- Commercial plan types differ by network and referral rules: HMO and EPO restrict members to network providers, PPO and POS allow out-of-network care at higher cost, and HDHP pairs a high deductible with a health savings account.
- HMO and POS plans typically require a primary care provider referral for specialists, while PPO and EPO plans usually do not.
- Coordination of Benefits (COB) determines which plan pays first when a patient has more than one coverage.
- A subscriber is always primary for their own claims; for a dependent child covered by two parents, the Birthday Rule makes the parent whose birthday falls earlier in the calendar year primary.
- Auto, no-fault, and liability coverage are primary for accident-related care, and the health plan may pursue subrogation to recover what it paid.
Commercial Plan Types
Quick Answer: Commercial plans differ in how strictly they limit you to a network and whether you need a referral. When a patient has two plans, Coordination of Benefits decides which one pays first — and for a child covered by both parents, the Birthday Rule applies.
Commercial insurance is private coverage, usually offered through an employer or purchased individually. Billers must identify the plan type because it dictates network rules, referral and authorization requirements, and patient cost-sharing.
Comparing Plan Types
| Plan Type | Network Rule | Referral Needed | Out-of-Network Coverage |
|---|---|---|---|
| HMO (Health Maintenance Organization) | Must use network providers | Yes — PCP referral for specialists | Generally none except emergencies |
| PPO (Preferred Provider Organization) | Network preferred, not required | No | Covered at higher patient cost |
| POS (Point of Service) | Network-based with out-of-network option | Yes — PCP referral | Covered at higher patient cost |
| EPO (Exclusive Provider Organization) | Must use network providers | No | Generally none except emergencies |
| HDHP (High-Deductible Health Plan) | Varies by underlying network | Varies | Varies; paired with an HSA |
An HDHP pairs a high deductible with a tax-advantaged Health Savings Account (HSA). Patients pay most early costs out of pocket until the deductible is met.
Referral and Authorization
A referral is approval from a primary care provider to see a specialist; HMO and POS plans typically require one. Prior authorization is the payer's advance approval of a specific service or drug and is separate from a referral. Missing either one is a frequent denial reason.
In-Network vs Out-of-Network
In-network providers have a contracted rate with the plan, so the patient pays lower cost-sharing. Out-of-network (OON) care, when covered at all, uses higher deductibles and coinsurance and may expose the patient to balance billing where permitted.
Coordination of Benefits (COB)
Coordination of Benefits (COB) is the process of determining the payment order when a patient has more than one health plan. The primary plan pays first as if it were the only coverage; the secondary plan then considers the remaining balance.
Determining the Primary Plan
| Situation | Primary Plan |
|---|---|
| Patient is the subscriber on their own plan | The patient's own plan (employee-as-employee) |
| Patient is covered as an employee on one plan and a dependent on another | The plan where the patient is the employee/subscriber |
| Dependent child covered by two parents' plans | The plan of the parent whose birthday falls earlier in the calendar year (Birthday Rule) |
| Child of divorced parents with a court decree | The plan named by the court decree |
| Active employee vs retiree coverage | The active employee plan |
The Birthday Rule compares only the month and day of each parent's birthday, not the year — the older parent is not automatically primary.
CMS COB Hierarchy
Medicare follows a defined Medicare Secondary Payer (MSP) order. In general, an employer group health plan pays before Medicare for actively working beneficiaries (or their spouse) at larger employers, and workers' compensation, no-fault, and liability insurance pay before Medicare for accident-related care.
Auto, No-Fault, and Liability Subrogation
When care results from an accident, auto, no-fault (Personal Injury Protection), or liability coverage is usually primary. If the health plan pays first, it may pursue subrogation — recovering its payment from the at-fault party or the liability settlement. Billers must capture accident details so claims route to the correct payer.
A child is covered under both parents' health plans. The mother's birthday is March 4 and the father's birthday is September 12. Under the Birthday Rule, which plan is primary for the child?
Which commercial plan type generally requires a primary care provider referral before seeing a specialist?
A patient is injured in an auto accident and treated. Which coverage is generally primary for the accident-related care?