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Denial Code Lookup Tool

Covers 18 of the most common CARC/RARC denial codes billers actually see on remittances. Search by code or keyword and get a plain-English answer instead of digging through a payer manual.

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Denial Code Lookup

Type a code (CO 45, PR 119) or a keyword from your remittance and get an instant, plain-English answer: what it means, who owes the balance, and what to do next.

Showing all 18 codes in the library. Start typing to filter.

CO 16Contractual Obligation
Practice write-off

Claim lacks information or has a submission error.

Claim/service lacks information or has submission/billing error(s) which is needed for adjudication.

What to do

Read the paired remark code (often M76, N290, or MA04), fix the missing data, and resubmit. Not an appeal situation.

Read the full CO 16 guide
CO 18Contractual Obligation
Practice write-off

Exact duplicate claim or service.

Exact duplicate claim/service.

What to do

Confirm whether the original claim already paid before resubmitting blindly.

CO 22Contractual Obligation
Practice write-off

Care may be covered by another payer (coordination of benefits).

This care may be covered by another payer per coordination of benefits.

What to do

Verify which plan is primary, confirm the patient's other coverage, and rebill in the right order.

Read the full CO 22 guide
CO 29Contractual Obligation
Practice write-off

Timely filing limit expired.

The time limit for filing has expired.

What to do

Appeal only with proof of original timely submission, or documented good cause.

Read the full CO 29 guide
CO 45Contractual Obligation
Practice write-off

Charge exceeds the contracted fee schedule.

Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement.

What to do

Usually a routine contractual adjustment. Audit periodically to catch underpayments where the payer's math is wrong.

Read the full CO 45 guide
CO 50Contractual Obligation
Practice write-off

Not medically necessary per the payer's policy.

These are non-covered services because this is not deemed a 'medical necessity' by the payer.

What to do

Appeal with clinical documentation matched point-by-point against the payer's LCD/NCD or medical policy criteria.

Read the full CO 50 guide
CO 97Contractual Obligation
Practice write-off

Bundled into another paid service.

The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.

What to do

Check the NCCI edit pair and the procedure's global period. Add modifier 59/X or 24/58/78/79 only when documentation supports a truly distinct service.

Read the full CO 97 guide
CO 109Contractual Obligation
Practice write-off

Wrong payer; the claim belongs elsewhere.

Claim/service not covered by this payer/contractor. You must send the claim/service to the correct payer/contractor.

What to do

Identify the correct payer or contractor (common with Medicare Advantage vs. traditional Medicare mix-ups) and submit there.

PR 119Patient Responsibility
Patient billable

Benefit maximum reached for the period.

Benefit maximum for this time period or occurrence has been reached.

What to do

Verify the plan's accumulator is accurate, then bill the patient or check for secondary coverage.

Read the full PR 119 guide
CO 151Contractual Obligation
Practice write-off

Frequency of services exceeds payer policy.

Payment adjusted because the payer deems the information submitted does not support this many/frequency of services.

What to do

Check the payer's frequency limits for the code, and appeal with medical-necessity documentation if the frequency was clinically justified.

CO 197Contractual Obligation
Practice write-off

Missing prior authorization or precertification.

Precertification/authorization/notification/pre-treatment absent.

What to do

Request retroactive authorization where the payer allows it; otherwise appeal with documented cause for the missed auth.

CO 236Contractual Obligation
Practice write-off

Procedure/modifier combination not compatible (NCCI edit).

This procedure or procedure/modifier combination is not compatible with another procedure or procedure/modifier combination provided on the same day according to the National Correct Coding Initiative.

What to do

Review the NCCI edit pair and its modifier indicator. Correct the coding, or apply modifier 59/X only when the services were genuinely distinct.

Read the full CO 236 guide
CO 253Contractual Obligation
Practice write-off

Medicare sequestration reduction (2%).

Sequestration - reduction in federal payment.

What to do

This is an informational federal reduction. Post it as its own adjustment category and never bill the patient for it.

Read the full CO 253 guide
PR 1Patient Responsibility
Patient billable

Patient's deductible.

Deductible amount.

What to do

Bill the patient; collect at point of service where possible.

PR 2Patient Responsibility
Patient billable

Patient's coinsurance.

Coinsurance amount.

What to do

Bill the patient; collect at point of service where possible.

PR 3Patient Responsibility
Patient billable

Patient's copay.

Co-payment amount.

What to do

Bill the patient; collect at point of service where possible.

PR 27Patient Responsibility
Patient billable

Coverage terminated before the date of service.

Expenses incurred after coverage terminated.

What to do

Re-verify the termination date; if coverage looks active elsewhere, bill that plan. Otherwise bill the patient.

Read the full PR 27 guide
PR 204Patient Responsibility
Patient billable

Service not covered under the patient's plan.

This service/equipment/drug is not covered under the patient's current benefit plan.

What to do

Confirm benefits, then bill the patient with any required advance notices (e.g. ABN) on file.

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