Coordination of Benefits Basics

Primary versus secondary is not guesswork

Coverage order can depend on plan rules, employment status, dependent coverage, Medicare coordination rules, accident coverage, and other factors.

Keep current coverage records

A patient's payer order can change. Reverify when insurance changes, employment changes, a new plan appears, or a payer requests updated COB information.

Use prior payer results

Secondary claims may require information from the primary payer's adjudication. Preserve the remittance or EOB and report amounts according to the secondary payer's rules.

Avoid duplicate billing

Document which payer received each version of the claim and which response is being used for the next step.

COB review before the next claim

• Verify which coverage is primary for the current date of service instead of relying on an old order.
• Keep the primary payer’s adjudication information available when billing a secondary plan.
• Update coverage records when employment, Medicare eligibility, dependent status, or other insurance changes.

Where to verify the rule

Requirements connected with coordination of benefits basics can vary by payer, plan, contract, program, and date of service. Verify the rule in the payer’s current provider manual, portal guidance, or other authoritative instructions rather than treating a prior claim as the rule.

Related guides

• CARC and RARC Basics for Medical Billing
• ICD-10 Diagnosis Codes: Billing Basics
• CPT and HCPCS Codes: Billing Basics