The five denial codes that cost practices the most

Denial management often gets organized around volume: work the biggest pile first. That is the wrong sort. Denials are enormously skewed by dollar value, and a hundred small office visit denials can be worth less than four surgical ones. Sort by dollars at risk and the queue reorders completely.

When a practice does that, the same few Claim Adjustment Reason Codes account for most of the exposure. They are worth understanding individually, because the fix for each is different and three of them are preventable before submission.

CARC 16: claim lacks information

The most common denial and the most misread. CARC 16 is not one problem, it is a container, and the actual cause sits in the accompanying Remittance Advice Remark Code. Working CARC 16 without reading the RARC is how practices end up resubmitting the same claim twice and getting the same denial back.

• N286 points at a missing or invalid referring provider identifier.
• MA27 and MA36 point at missing patient identity or name details.
• N382 means the patient could not be identified as insured at all.

Almost all of it is preventable. Validate the referring NPI at charge entry, check the member identifier format against the payer's published pattern, and require the subscriber relationship field rather than defaulting it to self.

CARC 197: precertification or authorization absent

The most expensive denial in most specialty practices, because it attaches to exactly the procedures that carry the largest charges. Imaging, surgery, infusion and durable medical equipment sit at the top of the list.

CARC 197 is also the denial with the weakest appeal position. If authorization was genuinely required and genuinely not obtained, the appeal usually fails, and the practice either writes it off or bills the patient depending on what the contract permits. That makes prevention the only real strategy.

The control that works is a CPT-level authorization matrix maintained per payer, checked at scheduling rather than at billing. By the time the charge is entered the service has already been rendered, which is far too late for the answer to be useful.

CARC 27: expenses incurred after coverage terminated

A pure eligibility failure, and the easiest of the five to eliminate. The patient's coverage ended before the date of service, and nobody checked. It shows up most in practices that verify eligibility at registration and never again, then see the patient monthly for a year.

Run a 270 eligibility request before every visit, not just the first one, and store the 271 response against the encounter. That stored response matters: when a payer later disputes coverage, a timestamped eligibility record is the difference between an appeal you win and one you cannot substantiate.

CARC 11: diagnosis inconsistent with the procedure

A coding problem rather than an administrative one, and the one most likely to indicate something systematically wrong rather than a one-off slip. It means the diagnosis submitted does not support medical necessity for the procedure under the payer's coverage policy.

Two causes dominate. The first is a diagnosis pointer error, where the correct code is on the claim but the line points at the wrong one. That is mechanical and a scrubber catches it. The second is genuine: the documented diagnosis does not meet the National or Local Coverage Determination for that service, which is a conversation with the provider, not a correction on the claim.

CARC 45: charge exceeds fee schedule

The odd one out, because it is usually not a denial at all. CARC 45 is a contractual adjustment: the payer paid its allowed amount and wrote the difference off against your contract. It appears in denial reports because reporting tools group all adjustment codes together.

It becomes a real problem in one case, which is worth watching for: when the allowed amount does not match the contracted rate. That is not a denial, it is an underpayment, and it will keep happening silently on every claim under that contract until somebody compares the remittance against the fee schedule.

Sorting the work

Three of the five never need to reach a payer. The remaining two are a coding conversation and a contracting one. None of them is solved by a larger follow-up team, which is why practices that staff their way out of a denial problem tend to find it waiting for them the following year.