Claims process

What is Coordination of benefits?

The rules that decide which of a patient’s plans pays first when they have more than one.

Also known as

COB · primary and secondary payer · order of benefits

Definition

When a patient carries multiple coverages, COB rules establish the order in which plans pay. The primary adjudicates first; the secondary then adjudicates the remainder with the primary’s remittance attached. Submitting to the wrong plan first produces a CO-22 or CO-109 and starts the whole sequence over.

A large share of COB denials come from stale payer records rather than provider error — an old employer plan still listed as primary, a terminated spouse’s policy still on file. Those can only be corrected by the patient contacting the payer, which makes them slow and worth catching at registration.

Why it matters

COB denials cost time twice: the claim has to be re-sequenced, and timely filing has been running at both payers the entire time.

Denial codes to know

CO-22 · Care may be covered by another payer OA-23 · Impact of prior payer adjudication CO-109 · Not covered by this payer — send to the correct payer

Related terms

Eligibility verification Timely filing

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