CO-102: Major Medical Adjustment

What Does CO-102 Mean?

CO-102 represents the contractual adjustment portion of the major medical benefit calculation. This is the amount the payer reduced from your billed charges based on the plan's major medical fee schedule or benefit structure. You cannot bill the patient for CO-102 — it is a write-off under your provider contract. This may represent the difference between billed charges and the allowed amount under the major medical tier, or it may reflect a benefit limit that has been reached.

CARC 102 surfaces when the payer adjudicates your claim under the major medical benefit tier of the patient's plan and applies an adjustment based on that tier's specific coverage rules. Many insurance plans divide benefits into tiers — basic and major medical — with different deductibles, coinsurance rates, and coverage limits for each. When a service falls under the major medical tier, the financial rules can differ significantly from basic benefits.

This code is particularly relevant for plans that maintain separate deductible and out-of-pocket accumulations for major medical services. A patient might have a fully satisfied basic deductible but still have an unmet major medical deductible, causing charges to be applied differently depending on the benefit category. The payer uses CARC 102 to signal that the adjustment is specifically a major medical benefit calculation, not a standard fee schedule reduction or coverage denial.

From a billing perspective, the first step is always to verify that the service was correctly categorized. Coding errors can cause a service to be adjudicated under the wrong benefit tier — for example, a procedure that should fall under basic benefits might be classified as major medical due to an incorrect CPT code or missing modifier. If the categorization is correct, the adjustment is a legitimate application of the plan's benefit structure, and your response depends on the group code: write off the CO portion and collect the PR portion from the patient.

Common Causes

How to Resolve

Verify the service was categorized under the correct benefit tier, then post the contractual adjustment and bill the patient for their major medical cost-sharing.

1. Verify the adjustment calculation Compare the CO-102 adjustment against the plan's major medical fee schedule or benefit limits. Confirm the payer applied the correct rates and limits.
2. Check for coding misclassification Verify the service was correctly classified under the major medical tier. If a coding error caused misclassification, correct the codes and resubmit.
3. Post the contractual write-off If the adjustment is correct, record the CO-102 amount as a contractual allowance. Tag it as a major medical adjustment for reporting purposes.
4. Appeal if the tier assignment is wrong If the service should have been adjudicated under basic benefits rather than major medical, file an appeal with documentation supporting the correct benefit category.

Common RARC Pairings

The RARC code tells you exactly what triggered the CO-102:

How to Prevent CO-102

• Verify the patient's benefit structure before rendering services, noting which services fall under basic vs. major medical
• Use accurate procedure and diagnosis codes to ensure claims are adjudicated under the correct benefit tier
• Check major medical benefit limits and deductible status before scheduling high-cost services
• Monitor claim remittances for patterns of major medical adjustments that may indicate systematic coding issues

General Prevention

• Verify the patient's benefit structure before rendering services, paying attention to whether the service falls under basic or major medical benefits
• Obtain prior authorization for services that fall under the major medical benefit tier when required by the payer
• Use accurate procedure and diagnosis codes to ensure claims are adjudicated under the correct benefit category
• Check the patient's remaining major medical benefits and maximums before scheduling services
• Educate patients about their major medical benefit structure, including deductibles, coinsurance, and maximums, before services are rendered
• Monitor claim remittances for patterns of major medical adjustments to identify systemic coding or billing issues

Also Filed As

The same CARC 102 may appear with different Group Codes:

Related Denial Codes