Most practices treat denials as paperwork. A claim comes back, someone fixes it, someone resubmits it, and the day moves on. That framing is what makes denials expensive.<\/p>\n
Every denied claim costs staff time to rework, delays payment by weeks, and carries a real chance of never being paid at all. Plenty of practices write off denials quietly once a claim ages past the point where chasing it costs more than the claim is worth. That write-off does not show up as a line item called “money we lost.” It shows up as a collection rate that never quite gets where it should be.<\/p>\n
Here is a useful way to think about it. If the same denial code appears on more than 5% of your claims in a given month, that is not bad luck. That is a workflow problem, and workflow problems are fixable.<\/p>\n
Below are the denials that show up most often in\u00a0US practices, what actually triggers each one, and what you change to stop it happening again. Strong revenue cycle management services<\/a> work backwards from the denial to the process that produced it<\/p>\n CO-16 is the denial that frustrates people most, because on its own it tells you almost nothing. It means something required was missing or wrong, without saying what.<\/p>\n The useful part is the remark code attached to it. CO-16 nearly always arrives with an N-series RARC that names the specific problem: a missing NPI, an absent referral number, no date of injury, an incomplete diagnosis field. Read the remark code first. Billers who skip straight to guessing what went wrong spend far longer on these than they need to.<\/p>\n Prevention happens at registration, not in billing. Most CO-16 denials trace back to a field nobody completed during intake. Build a short required-fields check into your intake process, and this category shrinks fast.<\/p>\n CO-97 means the service you billed was already paid inside another procedure. The payer considers the matter closed.<\/p>\n This one catches practices constantly because bundling rules are genuinely complicated and they change. The global surgical period is a common trap: 10 days for minor procedures, 90 days for major ones. Routine follow-up visits, wound checks, and related evaluation and management services inside that window are considered part of the surgical payment. Bill them separately and you get CO-97.<\/p>\n The fix is checking NCCI edits before submission rather than after denial, and applying the correct modifier when a service genuinely was distinct. A modifier applied correctly is legitimate. A modifier applied to force payment through is a compliance problem, so this is worth training on properly rather than leaving to habit.<\/p>\n Worth clearing up something here, because a lot of billing content gets it wrong.<\/p>\n CO-45 is usually not a denial. It is a contractual adjustment. It means you billed above the rate your contract with that payer allows, and the difference gets written off. There is nothing to appeal and nothing to resubmit.<\/p>\n What matters is the direction you check it in. If CO-45 adjustments are larger than you expected, the question is not whether the payer is right. The question is whether your contracted fee schedule in your billing system matches the fee schedule in the signed contract. Those drift apart more often than practices realise, particularly after a contract renewal that nobody updated in the system.<\/p>\n One thing you cannot do: bill the patient for a CO-45 amount. Contractual obligation adjustments are write-offs you agreed to. Billing the patient for one violates your payer contract.<\/p>\n These two get confused with each other and with CO-97, so the distinction is worth holding onto.<\/p>\n CO-97 means the service was a benefit, and it was already paid inside another code. CO-96 and CO-50 mean the service was never a covered benefit under that patient’s plan at all, or did not meet the payer’s medical necessity criteria.<\/p>\n Different problems, different fixes. Bundling denials are resolved through coding review. Coverage denials are resolved at eligibility verification, before the patient is seen. If a service is not covered, the patient needs to know that before treatment, not after.<\/p>\n Medical necessity denials are appealable when you have documentation supporting the clinical decision. Many practices do not appeal them, which is a shame, because appeals on medical necessity succeed more often than people assume when the clinical notes are genuinely there.<\/p>\n This is the most preventable denial on the list and one of the most common.<\/p>\n The service was performed, it was covered, it was medically necessary, and the payer will not pay because nobody got approval first. There is often no appeal path that works. The money is simply gone.<\/p>\n Some practices run prior authorization as an informal responsibility that sits with whoever has time. That is how these slip. Prior auth needs a named owner, a tracking log, and a rule that scheduled services requiring authorization do not get scheduled until the authorization number is recorded. It is boring administrative discipline, and it protects more revenue than almost anything else you can do.<\/p>\n Two details worth building into the process. Authorizations expire, so one obtained six weeks before a rescheduled procedure may no longer be valid on the day. And an approved authorization covers a specific procedure code, so if the procedure changes during the visit, the authorization may not cover what was actually done. Both situations produce a denial that looks unfair and is very hard to overturn.<\/p>\n Timely filing windows vary by payer and can be as short as 90 days. Miss it and the claim is unpayable, regardless of whether it was otherwise perfect.<\/p>\n CO-29 denials usually indicate one of two things: a claim that got stuck somewhere in the workflow and nobody noticed, or a secondary claim that waited too long on the primary payer. Both are visibility problems rather than skill problems.<\/p>\n An aging report reviewed weekly catches most of these. Reviewed monthly, it catches them too late.<\/p>\n CO-22 means the payer believes someone else is primary. Coordination of benefits is unglamorous and it causes a steady stream of denials, particularly with Medicare patients who also carry commercial coverage, and with paediatric patients covered under two parents.<\/p>\n Verifying coordination of benefits at each visit rather than at initial registration prevents most of it. Coverage changes and patients rarely think to mention it.<\/p>\n The diagnosis code submitted does not justify the service performed. Sometimes this is a genuine clinical documentation gap. More often it is a typo or a code selected from habit rather than from the note.<\/p>\n These are straightforward to correct and resubmit. They are also a good diagnostic signal in themselves. A rising CO-11 rate usually means a coding process issue, or a new staff member who needs support rather than correction.<\/p>\n The payer believes this claim was already submitted.<\/p>\n Sometimes that is correct, and the duplicate came from someone resubmitting a claim that was still processing. Sometimes it is wrong, and the original claim was genuinely never received.<\/p>\n The problem is that duplicates create noise that hides real issues. Staff learn to dismiss CO-18 as routine, and eventually dismiss one that was not. A clear rule about how long to wait before resubmitting anything, and a note in the system when a resubmission happens, keeps this manageable.<\/p>\n This does not have one single denial code, which is part of why it gets underestimated. It surfaces as coverage denials, wrong payer denials, and terminated policy denials.<\/p>\n The patient’s insurance changed. Or the policy lapsed. Or the plan the practice has on file is a year old. Nobody checked before the visit, and the claim goes out against coverage that no longer exists.<\/p>\n Eligibility verification before every visit, not just new patient visits, eliminates a meaningful share of total denials. It is the least interesting recommendation in this article and probably the highest return one.<\/p>\n Verification also needs to go beyond confirming that the policy is active. Active coverage does not tell you whether the specific service is covered, whether the deductible has been met, or whether the patient needs a referral. A check that confirms only “yes, they have insurance” still leaves you exposed to coverage and benefit denials later.<\/p>\n Individual fixes matter less than the process around them. Practices with low denial rates are rarely doing anything exotic. They are doing four ordinary things consistently.<\/p>\n They verify eligibility before every visit. They track prior authorizations against a list rather than against memory. They review denials by category each month instead of working them one at a time as they arrive. And they act on patterns rather than incidents.<\/p>\n That third point is where most practices lose ground. Working denials individually feels productive and it clears the queue, but it never tells you why the queue keeps filling. A monthly view by denial code shows you the two or three categories generating most of your rework, and those are almost always fixable at the front end.<\/p>\n If your denial rate sits in the 5 to 10% range and the same codes keep appearing, the cause is upstream of billing. It is in scheduling, registration, or eligibility. Fixing the claim is treating the symptom. Strong denial management services<\/a> work backwards from the denial to the process that produced it.<\/p>\n What Is A Normal Denial Rate For A Medical Practice?<\/strong><\/p>\n Most benchmarks put a healthy rate below 5%, though it varies by specialty. What matters more than the headline number is whether the same codes keep repeating. A 4% denial rate spread across many causes is a different problem from a 4% rate driven almost entirely by prior authorization failures.<\/p>\n Can A Denied Claim Be Appealed?<\/strong><\/p>\n Many can. Medical necessity denials, coverage disputes, and bundling decisions all have appeal paths. Timely filing denials and prior authorization failures usually do not, which is why prevention matters more for those two.<\/p>\n1. Missing Or Incomplete Information (CO-16)<\/strong><\/h2>\n
2. Bundled Services Billed Separately (CO-97)<\/strong><\/h2>\n
3. Charges Exceeding The Contracted Rate (CO-45)<\/strong><\/h2>\n
4. Service Not Covered By The Plan (CO-50 And CO-96)<\/strong><\/h2>\n
5. Prior Authorization Not Obtained (CO-197)<\/strong><\/h2>\n
6. Filing After The Deadline (CO-29)<\/strong><\/h2>\n
7. Wrong Payer Billed First (CO-22)<\/strong><\/h2>\n
8. Diagnosis Does Not Support The Procedure (CO-11)<\/strong><\/h2>\n
9. Duplicate Claim (CO-18)<\/strong><\/h2>\n
10. Eligibility Not Verified<\/strong><\/h2>\n
What To Do With All Of This<\/strong><\/h2>\n
Common Questions<\/strong><\/h2>\n